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Bulletproof AR15 bolt
If one were to build a bulletproof AR 15 bolt, meaning no cracking of
lug shearing with automatic use and slow wear , what material would you make it out of? What treatment processes would you do attain this strength? trg-s338 |
Bulletproof AR15 bolt
trg-s338 wrote:
If one were to build a bulletproof AR 15 bolt, meaning no cracking of lug shearing with automatic use and slow wear , what material would you make it out of? What treatment processes would you do attain this strength? trg-s338 K*********ium Heat treat by *************** *** ********** ***** ** ************ *** ****** finally ******** ** ************* *************** **. I*** * Censored by FSB |
Bulletproof AR15 bolt
"trg-s338" wrote in message
oups.com... If one were to build a bulletproof AR 15 bolt, meaning no cracking of lug shearing with automatic use and slow wear , what material would you make it out of? What treatment processes would you do attain this strength? trg-s338 obviously unobtanium is the correct material |
Bulletproof AR15 bolt
On Tue, 02 Oct 2007 01:04:38 -0000, trg-s338
wrote: If one were to build a bulletproof AR 15 bolt, meaning no cracking of lug shearing with automatic use and slow wear , what material would you make it out of? What treatment processes would you do attain this strength? trg-s338 Personally..Id buy one. They are cheap, and properly head treated and made of the proper materials. Im considering building a California AR, but will be using a commercial bolt. Gunner |
Bulletproof AR15 bolt
On Oct 2, 8:52 am, Gunner Asch wrote:
On Tue, 02 Oct 2007 01:04:38 -0000, trg-s338 wrote: If one were to build a bulletproof AR 15 bolt, meaning no cracking of lug shearing with automatic use and slow wear , what material would you make it out of? What treatment processes would you do attain this strength? trg-s338 Personally..Id buy one. They are cheap, and properly head treated and made of the proper materials. Im considering building a California AR, but will be using a commercial bolt. Gunner I apologise for failing to be more specific in the application. No need for better than what's available for the 223 but I've been considering a California AR15 in the 6.5mm Grendel. This round exerting higher preasure on the bolt has been reported to crack bolts of commercial origin or shear lugs. Even the developers of this round have had occassional failure in their bolts. The commercial rounds are downloaded to limit preasure development because of this weak link in the system. Just wondering if one could be built without the business considerations commercial manufacturers are subject to or limited by. Materials like any of the various tool steels or exotic metals like Inconel or other such materials able to handle the stresses of an AR bolt in this application, are any of these appropriate? trg-s338 |
Bulletproof AR15 bolt
"trg-s338" wrote in message s.com... On Oct 2, 8:52 am, Gunner Asch wrote: On Tue, 02 Oct 2007 01:04:38 -0000, trg-s338 wrote: If one were to build a bulletproof AR 15 bolt, meaning no cracking of lug shearing with automatic use and slow wear , what material would you make it out of? What treatment processes would you do attain this strength? trg-s338 Personally..Id buy one. They are cheap, and properly head treated and made of the proper materials. Im considering building a California AR, but will be using a commercial bolt. Gunner I apologise for failing to be more specific in the application. No need for better than what's available for the 223 but I've been considering a California AR15 in the 6.5mm Grendel. This round exerting higher preasure on the bolt has been reported to crack bolts of commercial origin or shear lugs. Even the developers of this round have had occassional failure in their bolts. The commercial rounds are downloaded to limit preasure development because of this weak link in the system. Just wondering if one could be built without the business considerations commercial manufacturers are subject to or limited by. Materials like any of the various tool steels or exotic metals like Inconel or other such materials able to handle the stresses of an AR bolt in this application, are any of these appropriate? Do you know the material and heat treatment of the original? If you want something better, you have to know what you're starting with. (When I was at Wasino we were facing those bolts in a trial run for Colt, but I don't remember the material. Sorry.) -- Ed Huntress |
Bulletproof AR15 bolt
On Oct 2, 1:26 pm, "Ed Huntress" wrote:
Do you know the material and heat treatment of the original? If you want something better, you have to know what you're starting with. (When I was at Wasino we were facing those bolts in a trial run for Colt, but I don't remember the material. Sorry.) Ed is certainly right. You could waste a lot of time and money by trying to reinvent the wheel. Off the cuff response: S-class tool steels are make for severe shock environments Things like blanking and cold-heading, where less rugged tool steels will shatter. You can also investigate powered-metallurgy tool steels. Bloody tough to machine (not for amateurs) and very expensive, but if you're able to build your part, it will likely be about as strong as can be made. You should discuss the application with a tool steel apps engineer. You'll also get information on proper heat-treat (likely impossible at home - will need to be farmed out). (this advise is worth exactly what you paid for it) Regards, Robin |
Bulletproof AR15 bolt
On Oct 2, 5:12 pm, "Robin S." wrote:
On Oct 2, 1:26 pm, "Ed Huntress" wrote: Do you know the material and heat treatment of the original? If you want something better, you have to know what you're starting with. (When I was at Wasino we were facing those bolts in a trial run for Colt, but I don't remember the material. Sorry.) Ed is certainly right. You could waste a lot of time and money by trying to reinvent the wheel. Off the cuff response: S-class tool steels are make for severe shock environments Things like blanking and cold-heading, where less rugged tool steels will shatter. You can also investigate powered-metallurgy tool steels. Bloody tough to machine (not for amateurs) and very expensive, but if you're able to build your part, it will likely be about as strong as can be made. You should discuss the application with a tool steel apps engineer. You'll also get information on proper heat-treat (likely impossible at home - will need to be farmed out). (this advise is worth exactly what you paid for it) Regards, Robin Thanks for at least attempting to answer my post. For my personal edification and learning, I will look up the materials you mentioned. Yes most heat treat processes are beyond my realm. |
Bulletproof AR15 bolt
On Tue, 02 Oct 2007 17:38:31 -0700, trg-s338
wrote: On Oct 2, 5:12 pm, "Robin S." wrote: On Oct 2, 1:26 pm, "Ed Huntress" wrote: Do you know the material and heat treatment of the original? If you want something better, you have to know what you're starting with. (When I was at Wasino we were facing those bolts in a trial run for Colt, but I don't remember the material. Sorry.) Ed is certainly right. You could waste a lot of time and money by trying to reinvent the wheel. Off the cuff response: S-class tool steels are make for severe shock environments Things like blanking and cold-heading, where less rugged tool steels will shatter. You can also investigate powered-metallurgy tool steels. Bloody tough to machine (not for amateurs) and very expensive, but if you're able to build your part, it will likely be about as strong as can be made. You should discuss the application with a tool steel apps engineer. You'll also get information on proper heat-treat (likely impossible at home - will need to be farmed out). (this advise is worth exactly what you paid for it) Regards, Robin Thanks for at least attempting to answer my post. For my personal edification and learning, I will look up the materials you mentioned. Yes most heat treat processes are beyond my realm. ======= There is another caution, the one about a chain not being any stronger than its weakest link. A super-stong bolt may cause the receiver to fail. If there is any group that cn shed some light on this it would be this one. Unka' George [George McDuffee] ============ Merchants have no country. The mere spot they stand on does not constitute so strong an attachment as that from which they draw their gains. Thomas Jefferson (1743-1826), U.S. president. Letter, 17 March 1814. |
Bulletproof AR15 bolt
On Tue, 02 Oct 2007 10:08:03 -0700, trg-s338
wrote: On Oct 2, 8:52 am, Gunner Asch wrote: On Tue, 02 Oct 2007 01:04:38 -0000, trg-s338 wrote: If one were to build a bulletproof AR 15 bolt, meaning no cracking of lug shearing with automatic use and slow wear , what material would you make it out of? What treatment processes would you do attain this strength? trg-s338 Personally..Id buy one. They are cheap, and properly head treated and made of the proper materials. Im considering building a California AR, but will be using a commercial bolt. Gunner I apologise for failing to be more specific in the application. No need for better than what's available for the 223 but I've been considering a California AR15 in the 6.5mm Grendel. This round exerting higher preasure on the bolt has been reported to crack bolts of commercial origin or shear lugs. Even the developers of this round have had occassional failure in their bolts. The commercial rounds are downloaded to limit preasure development because of this weak link in the system. Just wondering if one could be built without the business considerations commercial manufacturers are subject to or limited by. Materials like any of the various tool steels or exotic metals like Inconel or other such materials able to handle the stresses of an AR bolt in this application, are any of these appropriate? trg-s338 If you want to re-design the bolt of an AR15 then the first step is to determine what material and tensile strength, i.e., heat treatment, was used for the original bolt. As I believe the original bolt was chrome plated you will need to advise the testing lab of this fact. In addition chrome plating is known to be a source of hydrogen enbrittlement so the lab should also test for that. Once you have a lab report as to material and strength in hand you need to consult a competent engineer with experience in designing high strength steel components who can advise you of the feasibility of re-manufacturing the bolt. It may even be that given the pressures developed by the new cartridge that the present bolt design cannot be made to successfully withstand the pressures in which case you will need to redesign the locking system for these higher forces. This is probably not what you want to hear but the empirical method of "suck it and see" is going to bust a lot of receivers before you get it right. Bruce in Bangkok (brucepaigeATgmailDOTcom) |
Bulletproof AR15 bolt
JayCups wrote:
Hey Gunner, What comprises a California AR? What comes to mind is a single shot manual bolt with a 5' barrel, a flashing red warning light and GPS locator? Jay Cups, an exKalifornian now living in Texas Ha, don't forget the plugged barrel, and required permit only illegals can get. |
Bulletproof AR15 bolt
wrote in message ... snip If you want to re-design the bolt of an AR15 then the first step is to determine what material and tensile strength, i.e., heat treatment, was used for the original bolt. As I believe the original bolt was chrome plated you will need to advise the testing lab of this fact. In addition chrome plating is known to be a source of hydrogen enbrittlement so the lab should also test for that. Once you have a lab report as to material and strength in hand you need to consult a competent engineer with experience in designing high strength steel components who can advise you of the feasibility of re-manufacturing the bolt. It may even be that given the pressures developed by the new cartridge that the present bolt design cannot be made to successfully withstand the pressures in which case you will need to redesign the locking system for these higher forces. This is probably not what you want to hear but the empirical method of "suck it and see" is going to bust a lot of receivers before you get it right. Bruce in Bangkok (brucepaigeATgmailDOTcom) If you call Colt and persist, they'll probably tell you what it's made of. Just don't tell them you want to improve it. g -- Ed Huntress |
Bulletproof AR15 bolt
so what is the difference between the California bolt and stock standard
bolt? what about the gas hole size for the barrel, since this will effect cycle rate? how different is this size than the 6.8 that is available now? "JayCups" wrote in message ... Hey Gunner, What comprises a California AR? What comes to mind is a single shot manual bolt with a 5' barrel, a flashing red warning light and GPS locator? Jay Cups, an exKalifornian now living in Texas Gunner Asch wrote: On Tue, 02 Oct 2007 01:04:38 -0000, trg-s338 wrote: If one were to build a bulletproof AR 15 bolt, meaning no cracking of lug shearing with automatic use and slow wear , what material would you make it out of? What treatment processes would you do attain this strength? trg-s338 Personally..Id buy one. They are cheap, and properly head treated and made of the proper materials. Im considering building a California AR, but will be using a commercial bolt. Gunner |
Bulletproof AR15 bolt
Keywords:
In article .com, trg-s338 wrote: One big difference in AR bolts is how they are treated & tested after manufacturing. Real Colt bolts are shot-peened (stress releaved?), magnetic particle tested for cracks, and supposedly proof tested somehow. I'm not sure if this is done separate from proof testing of the rifles or not. There are a few 3rd party bolts that are shot peened & MP tested, but I don't know of anyone else who proof tests their bolts. This is why Colt bolts are extra pricey, aside from the usual markup for just being Colt. Doug White |
Bulletproof AR15 bolt
"Doug White" wrote in message ... Keywords: In article .com, trg-s338 wrote: One big difference in AR bolts is how they are treated & tested after manufacturing. Real Colt bolts are shot-peened (stress releaved?) FWIW, shot-peening actually work-hardens and compresses the surface, making the bolt much more resistant to initiating stress cracks and adding just a bit of strength overall. I've never heard about it in relation to stress-relieving but I suppose it's possible. Shot-peening often is used on steel connecting rods for racing engines for the same purpose. -- Ed Huntress |
Bulletproof AR15 bolt
On Oct 2, 6:41 pm, wrote:
On Tue, 02 Oct 2007 10:08:03 -0700, trg-s338 wrote: On Oct 2, 8:52 am, Gunner Asch wrote: On Tue, 02 Oct 2007 01:04:38 -0000, trg-s338 wrote: If one were to build a bulletproof AR 15 bolt, meaning no cracking of lug shearing with automatic use and slow wear , what material would you make it out of? What treatment processes would you do attain this strength? trg-s338 Personally..Id buy one. They are cheap, and properly head treated and made of the proper materials. Im considering building a California AR, but will be using a commercial bolt. Gunner I apologise for failing to be more specific in the application. No need for better than what's available for the 223 but I've been considering a California AR15 in the 6.5mm Grendel. This round exerting higher preasure on the bolt has been reported to crack bolts of commercial origin or shear lugs. Even the developers of this round have had occassional failure in their bolts. The commercial rounds are downloaded to limit preasure development because of this weak link in the system. Just wondering if one could be built without the business considerations commercial manufacturers are subject to or limited by. Materials like any of the various tool steels or exotic metals like Inconel or other such materials able to handle the stresses of an AR bolt in this application, are any of these appropriate? trg-s338 If you want to re-design the bolt of an AR15 then the first step is to determine what material and tensile strength, i.e., heat treatment, was used for the original bolt. As I believe the original bolt was chrome plated you will need to advise the testing lab of this fact. In addition chrome plating is known to be a source of hydrogen enbrittlement so the lab should also test for that. Once you have a lab report as to material and strength in hand you need to consult a competent engineer with experience in designing high strength steel components who can advise you of the feasibility of re-manufacturing the bolt. It may even be that given the pressures developed by the new cartridge that the present bolt design cannot be made to successfully withstand the pressures in which case you will need to redesign the locking system for these higher forces. This is probably not what you want to hear but the empirical method of "suck it and see" is going to bust a lot of receivers before you get it right. Bruce in Bangkok (brucepaigeATgmailDOTcom) You are probably correct in that the bolt as designed was not meant to handle the increased preasure of a bigger cartridge, and that to successfully get the bolt reliable, a major redesign of the lockup system needs to be addressed. All that is of course beyond the tinkering/hobby realm of mine. Busting a lot of receivers through bolt lug shearing, lockup failure and the resultant explosion is not my cup of tea either. Thanks for the response. PS-- |
Bulletproof AR15 bolt
On Oct 2, 6:20 pm, F. George McDuffee gmcduf...@mcduffee-
associates.us wrote: On Tue, 02 Oct 2007 17:38:31 -0700, trg-s338 wrote: On Oct 2, 5:12 pm, "Robin S." wrote: On Oct 2, 1:26 pm, "Ed Huntress" wrote: Do you know the material and heat treatment of the original? If you want something better, you have to know what you're starting with. (When I was at Wasino we were facing those bolts in a trial run for Colt, but I don't remember the material. Sorry.) Ed is certainly right. You could waste a lot of time and money by trying to reinvent the wheel. Off the cuff response: S-class tool steels are make for severe shock environments Things like blanking and cold-heading, where less rugged tool steels will shatter. You can also investigate powered-metallurgy tool steels. Bloody tough to machine (not for amateurs) and very expensive, but if you're able to build your part, it will likely be about as strong as can be made. You should discuss the application with a tool steel apps engineer. You'll also get information on proper heat-treat (likely impossible at home - will need to be farmed out). (this advise is worth exactly what you paid for it) Regards, Robin Thanks for at least attempting to answer my post. For my personal edification and learning, I will look up the materials you mentioned. Yes most heat treat processes are beyond my realm. ======= There is another caution, the one about a chain not being any stronger than its weakest link. A super-stong bolt may cause the receiver to fail. If there is any group that cn shed some light on this it would be this one. Unka' George [George McDuffee] ============ Merchants have no country. The mere spot they stand on does not constitute so strong an attachment as that from which they draw their gains. Thomas Jefferson (1743-1826), U.S. president. Letter, 17 March 1814. It is my understanding that on the AR15, the bolt and barrel extension lockup take up all the stress. The receiver is there essentially just to give the bolt carrier something to ride in, assuming the gas system is tuned properly. Perhaps I'm missing something with reguards to the point of what significantly stresses the receiver in the AR15 system? |
Bulletproof AR15 bolt
On Oct 3, 3:02 pm, "jay s" wrote:
so what is the difference between the California bolt and stock standard bolt? what about the gas hole size for the barrel, since this will effect cycle rate? how different is this size than the 6.8 that is available now? "JayCups" wrote in message ... Hey Gunner, What comprises a California AR? What comes to mind is a single shot manual bolt with a 5' barrel, a flashing red warning light and GPS locator? Jay Cups, an exKalifornian now living in Texas Gunner Asch wrote: On Tue, 02 Oct 2007 01:04:38 -0000, trg-s338 wrote: If one were to build a bulletproof AR 15 bolt, meaning no cracking of lug shearing with automatic use and slow wear , what material would you make it out of? What treatment processes would you do attain this strength? trg-s338 Personally..Id buy one. They are cheap, and properly head treated and made of the proper materials. Im considering building a California AR, but will be using a commercial bolt. Gunner The California AR is basically a rifle with a permanently mounted 10 round magazine, or a removeable magazine but no handle on the rifle. To load the fixed magazine, you would have to break open the upper from the lower receiver and use stripper clips or manually load. There is no difference between CA AR bolt and standard commercial bolt but using other cartridges of course requires specific sizing of the bolt face. |
Bulletproof AR15 bolt
On Thu, 04 Oct 2007 04:46:29 -0000, trg-s338
wrote: On Oct 2, 6:41 pm, wrote: On Tue, 02 Oct 2007 10:08:03 -0700, trg-s338 wrote: On Oct 2, 8:52 am, Gunner Asch wrote: On Tue, 02 Oct 2007 01:04:38 -0000, trg-s338 wrote: If one were to build a bulletproof AR 15 bolt, meaning no cracking of lug shearing with automatic use and slow wear , what material would you make it out of? What treatment processes would you do attain this strength? trg-s338 Personally..Id buy one. They are cheap, and properly head treated and made of the proper materials. Im considering building a California AR, but will be using a commercial bolt. Gunner I apologise for failing to be more specific in the application. No need for better than what's available for the 223 but I've been considering a California AR15 in the 6.5mm Grendel. This round exerting higher preasure on the bolt has been reported to crack bolts of commercial origin or shear lugs. Even the developers of this round have had occassional failure in their bolts. The commercial rounds are downloaded to limit preasure development because of this weak link in the system. Just wondering if one could be built without the business considerations commercial manufacturers are subject to or limited by. Materials like any of the various tool steels or exotic metals like Inconel or other such materials able to handle the stresses of an AR bolt in this application, are any of these appropriate? trg-s338 If you want to re-design the bolt of an AR15 then the first step is to determine what material and tensile strength, i.e., heat treatment, was used for the original bolt. As I believe the original bolt was chrome plated you will need to advise the testing lab of this fact. In addition chrome plating is known to be a source of hydrogen enbrittlement so the lab should also test for that. Once you have a lab report as to material and strength in hand you need to consult a competent engineer with experience in designing high strength steel components who can advise you of the feasibility of re-manufacturing the bolt. It may even be that given the pressures developed by the new cartridge that the present bolt design cannot be made to successfully withstand the pressures in which case you will need to redesign the locking system for these higher forces. This is probably not what you want to hear but the empirical method of "suck it and see" is going to bust a lot of receivers before you get it right. Bruce in Bangkok (brucepaigeATgmailDOTcom) You are probably correct in that the bolt as designed was not meant to handle the increased preasure of a bigger cartridge, and that to successfully get the bolt reliable, a major redesign of the lockup system needs to be addressed. All that is of course beyond the tinkering/hobby realm of mine. Busting a lot of receivers through bolt lug shearing, lockup failure and the resultant explosion is not my cup of tea either. Thanks for the response. PS-- You know, I've been thinking about your problem and it seems funny to me that bolt lugs are cracking. Years ago P.O. Ackley did some tests on the actual thrust exerted on the bolt when the gun is fired and if I remember correctly because of the cartridge expanding as the powder burns it grips the sides of the chamber and actual thrust forces, against the bolt were far lower then chamber pressure would have one believe. Another point, many bolt guns are converted to higher power cartridges then originally intended, witness some of the chamberings for the poor old '98 Mauser, military, that has a relatively weak (compared to modern actions) bolt and receiver. How much higher chamber pressure is this new round developing and what is the cartridge head size compared to the normal AR-15? Another point, if you are firing a higher powered cartridge then unless you either limit the amount of gas vented to the action, increase the weight of the bolt and carrier or increase the strength of the recoil spring the bolt is going to slam back against the stops with considerable more force then normal. Might this have any effect on bolt cracking? If chamber pressure is higher then gas pressure is higher - is the bolt starting to unlock earlier in the cycle so that higher pressure is exerted against a partially opened lock? These are just random thoughts but it might be interesting to see what happens if, say a gas port is plugged or a very heavy recoil spring fitted. Bruce in Bangkok (brucepaigeATgmailDOTcom) |
Bulletproof AR15 bolt
On Oct 4, 1:12 am, wrote:
On Thu, 04 Oct 2007 04:46:29 -0000, trg-s338 wrote: On Oct 2, 6:41 pm, wrote: On Tue, 02 Oct 2007 10:08:03 -0700, trg-s338 wrote: On Oct 2, 8:52 am, Gunner Asch wrote: On Tue, 02 Oct 2007 01:04:38 -0000, trg-s338 wrote: If one were to build a bulletproof AR 15 bolt, meaning no cracking of lug shearing with automatic use and slow wear , what material would you make it out of? What treatment processes would you do attain this strength? trg-s338 Personally..Id buy one. They are cheap, and properly head treated and made of the proper materials. Im considering building a California AR, but will be using a commercial bolt. Gunner I apologise for failing to be more specific in the application. No need for better than what's available for the 223 but I've been considering a California AR15 in the 6.5mm Grendel. This round exerting higher preasure on the bolt has been reported to crack bolts of commercial origin or shear lugs. Even the developers of this round have had occassional failure in their bolts. The commercial rounds are downloaded to limit preasure development because of this weak link in the system. Just wondering if one could be built without the business considerations commercial manufacturers are subject to or limited by. Materials like any of the various tool steels or exotic metals like Inconel or other such materials able to handle the stresses of an AR bolt in this application, are any of these appropriate? trg-s338 If you want to re-design the bolt of an AR15 then the first step is to determine what material and tensile strength, i.e., heat treatment, was used for the original bolt. As I believe the original bolt was chrome plated you will need to advise the testing lab of this fact. In addition chrome plating is known to be a source of hydrogen enbrittlement so the lab should also test for that. Once you have a lab report as to material and strength in hand you need to consult a competent engineer with experience in designing high strength steel components who can advise you of the feasibility of re-manufacturing the bolt. It may even be that given the pressures developed by the new cartridge that the present bolt design cannot be made to successfully withstand the pressures in which case you will need to redesign the locking system for these higher forces. This is probably not what you want to hear but the empirical method of "suck it and see" is going to bust a lot of receivers before you get it right. Bruce in Bangkok (brucepaigeATgmailDOTcom) You are probably correct in that the bolt as designed was not meant to handle the increased preasure of a bigger cartridge, and that to successfully get the bolt reliable, a major redesign of the lockup system needs to be addressed. All that is of course beyond the tinkering/hobby realm of mine. Busting a lot of receivers through bolt lug shearing, lockup failure and the resultant explosion is not my cup of tea either. Thanks for the response. PS-- You know, I've been thinking about your problem and it seems funny to me that bolt lugs are cracking. Years ago P.O. Ackley did some tests on the actual thrust exerted on the bolt when the gun is fired and if I remember correctly because of the cartridge expanding as the powder burns it grips the sides of the chamber and actual thrust forces, against the bolt were far lower then chamber pressure would have one believe. Another point, many bolt guns are converted to higher power cartridges then originally intended, witness some of the chamberings for the poor old '98 Mauser, military, that has a relatively weak (compared to modern actions) bolt and receiver. How much higher chamber pressure is this new round developing and what is the cartridge head size compared to the normal AR-15? Another point, if you are firing a higher powered cartridge then unless you either limit the amount of gas vented to the action, increase the weight of the bolt and carrier or increase the strength of the recoil spring the bolt is going to slam back against the stops with considerable more force then normal. Might this have any effect on bolt cracking? If chamber pressure is higher then gas pressure is higher - is the bolt starting to unlock earlier in the cycle so that higher pressure is exerted against a partially opened lock? These are just random thoughts but it might be interesting to see what happens if, say a gas port is plugged or a very heavy recoil spring fitted. Bruce in Bangkok (brucepaigeATgmailDOTcom) I believe the developer of the 6.5 Grendel cartridge, Alexander Arms, has worked out the fine details of tuning the gas system. In fact the blueprint for the chamber and other system parts specific to the Grendel gun are proprietary if only by name. They still get the occassional problem with the bolt as I've delineated in my original post. trg-s338 |
Bulletproof AR15 bolt
"trg-s338" wrote in message ps.com... On Oct 4, 1:12 am, wrote: On Thu, 04 Oct 2007 04:46:29 -0000, trg-s338 wrote: On Oct 2, 6:41 pm, wrote: On Tue, 02 Oct 2007 10:08:03 -0700, trg-s338 wrote: On Oct 2, 8:52 am, Gunner Asch wrote: On Tue, 02 Oct 2007 01:04:38 -0000, trg-s338 wrote: If one were to build a bulletproof AR 15 bolt, meaning no cracking of lug shearing with automatic use and slow wear , what material would you make it out of? What treatment processes would you do attain this strength? trg-s338 Personally..Id buy one. They are cheap, and properly head treated and made of the proper materials. Im considering building a California AR, but will be using a commercial bolt. Gunner I apologise for failing to be more specific in the application. No need for better than what's available for the 223 but I've been considering a California AR15 in the 6.5mm Grendel. This round exerting higher preasure on the bolt has been reported to crack bolts of commercial origin or shear lugs. Even the developers of this round have had occassional failure in their bolts. The commercial rounds are downloaded to limit preasure development because of this weak link in the system. Just wondering if one could be built without the business considerations commercial manufacturers are subject to or limited by. Materials like any of the various tool steels or exotic metals like Inconel or other such materials able to handle the stresses of an AR bolt in this application, are any of these appropriate? trg-s338 If you want to re-design the bolt of an AR15 then the first step is to determine what material and tensile strength, i.e., heat treatment, was used for the original bolt. As I believe the original bolt was chrome plated you will need to advise the testing lab of this fact. In addition chrome plating is known to be a source of hydrogen enbrittlement so the lab should also test for that. Once you have a lab report as to material and strength in hand you need to consult a competent engineer with experience in designing high strength steel components who can advise you of the feasibility of re-manufacturing the bolt. It may even be that given the pressures developed by the new cartridge that the present bolt design cannot be made to successfully withstand the pressures in which case you will need to redesign the locking system for these higher forces. This is probably not what you want to hear but the empirical method of "suck it and see" is going to bust a lot of receivers before you get it right. Bruce in Bangkok (brucepaigeATgmailDOTcom) You are probably correct in that the bolt as designed was not meant to handle the increased preasure of a bigger cartridge, and that to successfully get the bolt reliable, a major redesign of the lockup system needs to be addressed. All that is of course beyond the tinkering/hobby realm of mine. Busting a lot of receivers through bolt lug shearing, lockup failure and the resultant explosion is not my cup of tea either. Thanks for the response. PS-- You know, I've been thinking about your problem and it seems funny to me that bolt lugs are cracking. Years ago P.O. Ackley did some tests on the actual thrust exerted on the bolt when the gun is fired and if I remember correctly because of the cartridge expanding as the powder burns it grips the sides of the chamber and actual thrust forces, against the bolt were far lower then chamber pressure would have one believe. Another point, many bolt guns are converted to higher power cartridges then originally intended, witness some of the chamberings for the poor old '98 Mauser, military, that has a relatively weak (compared to modern actions) bolt and receiver. How much higher chamber pressure is this new round developing and what is the cartridge head size compared to the normal AR-15? Another point, if you are firing a higher powered cartridge then unless you either limit the amount of gas vented to the action, increase the weight of the bolt and carrier or increase the strength of the recoil spring the bolt is going to slam back against the stops with considerable more force then normal. Might this have any effect on bolt cracking? If chamber pressure is higher then gas pressure is higher - is the bolt starting to unlock earlier in the cycle so that higher pressure is exerted against a partially opened lock? These are just random thoughts but it might be interesting to see what happens if, say a gas port is plugged or a very heavy recoil spring fitted. Bruce in Bangkok (brucepaigeATgmailDOTcom) I believe the developer of the 6.5 Grendel cartridge, Alexander Arms, has worked out the fine details of tuning the gas system. In fact the blueprint for the chamber and other system parts specific to the Grendel gun are proprietary if only by name. They still get the occassional problem with the bolt as I've delineated in my original post. I see that the case head diameter of the 6.5 Grendel is 0.445". The diameter of the .223 is 0.375". So you do have some force issues to deal with in the bolt with the larger cartridge, assuming equal pressures. Frankly, I'm skeptical that you're going to improve much on the original Colt item. It may be possible to do so with some expertise in both materials and machining, but Colt probably has it developed pretty far as it is. You want to avoid the temptation to achieve greater strength or wear life through greater hardness of the bolt. That probably would be dangerous. Is there any possibility of increasing the contact area of the lugs? I'm not familiar with the internal design of the AR-15. -- Ed Huntress |
Bulletproof AR15 bolt
"Randal O'Brian" wrote in message ... "Ed Huntress" wrote in message ... snip Is there any possibility of increasing the contact area of the lugs? I'm not familiar with the internal design of the AR-15. -- Ed Huntress It would require a redesign. the original .54" dia. bolt head has 7 radial lugs relatively evenly spaced (except for the extractor/feed rib gap) that are about .103" wide, .279" long, and .095" high. Total shear area is about 0.201 sq.in. Contact area is a little less than 0.068 sq. in. It locks by rotation into the barrel extension(screwed onto the barrel) So a heftier lock-up would entail a new bolt and extension which there probably is room for in a AR15 upper receiver. Randy That all sounds like it would be tough to improve what you have. I'll bet you'll find that the military specification on the bolt is pretty demanding. Good luck in your quest. -- Ed Huntress |
Bulletproof AR15 bolt
A little checking indicates that the M16/AR15 bolt is a pretty slick piece
of metal, as I suspected. It's both case-hardened and shot peened (to SAE AMS S 13165 specification). The technical details on materials and so on are available as mil spec 8448510, but you have to sign a non-disclosure and non-use agreement to get it. Brownell's sells a Teflon-coated version that meets the spec, and the bolt in the Bushmaster apparently does, too. You may be able to get the material spec from them. When you see an alloy steel that's case-hardened and shot-peened, you can be fairly sure it's being pushed to limits on both strength and toughness. Trying to get the same properties just by substituting steel grades seems problematic. BTW, there's an interesting-sounding article on M16 bolt failures that you can get for $30. You can read the abstract for free. Go to http://www.sciencedirect.com and search on "Failure analysis of the M16 rifle bolt" -- Ed Huntress |
Bulletproof AR15 bolt
trg-s338 wrote:
I believe the developer of the 6.5 Grendel cartridge, Alexander Arms, has worked out the fine details of tuning the gas system. In fact the blueprint for the chamber and other system parts specific to the Grendel gun are proprietary if only by name. They still get the occassional problem with the bolt as I've delineated in my original post. Its been a while since I had my hands on a M-16, I remember that the bolt has a lot of lugs and a very short arc obviously. For those that never saw one it looks like a short coarse splined shaft. What is the length of the mating 'splines' in the barrel extension compared to those of the bolt? If the bolts are failing, it would seem they would have the shorter length. Wes |
Bulletproof AR15 bolt
On Thu, 04 Oct 2007 04:47:49 -0000, trg-s338
wrote: On Oct 2, 6:20 pm, F. George McDuffee gmcduf...@mcduffee- associates.us wrote: On Tue, 02 Oct 2007 17:38:31 -0700, trg-s338 wrote: On Oct 2, 5:12 pm, "Robin S." wrote: On Oct 2, 1:26 pm, "Ed Huntress" wrote: Do you know the material and heat treatment of the original? If you want something better, you have to know what you're starting with. (When I was at Wasino we were facing those bolts in a trial run for Colt, but I don't remember the material. Sorry.) Ed is certainly right. You could waste a lot of time and money by trying to reinvent the wheel. Off the cuff response: S-class tool steels are make for severe shock environments Things like blanking and cold-heading, where less rugged tool steels will shatter. You can also investigate powered-metallurgy tool steels. Bloody tough to machine (not for amateurs) and very expensive, but if you're able to build your part, it will likely be about as strong as can be made. You should discuss the application with a tool steel apps engineer. You'll also get information on proper heat-treat (likely impossible at home - will need to be farmed out). (this advise is worth exactly what you paid for it) Regards, Robin Thanks for at least attempting to answer my post. For my personal edification and learning, I will look up the materials you mentioned. Yes most heat treat processes are beyond my realm. ======= There is another caution, the one about a chain not being any stronger than its weakest link. A super-stong bolt may cause the receiver to fail. If there is any group that cn shed some light on this it would be this one. Unka' George [George McDuffee] ============ Merchants have no country. The mere spot they stand on does not constitute so strong an attachment as that from which they draw their gains. Thomas Jefferson (1743-1826), U.S. president. Letter, 17 March 1814. It is my understanding that on the AR15, the bolt and barrel extension lockup take up all the stress. The receiver is there essentially just to give the bolt carrier something to ride in, assuming the gas system is tuned properly. Perhaps I'm missing something with reguards to the point of what significantly stresses the receiver in the AR15 system? You are correct. Which is why the receivers can be made from Aluminum. The bolt is locked into the barrel at the moment of fireing until the pressure drops enough for the gas piston to unlock the bolt and push it to the rear. The receiver is just a chunk of metal to keep everything in line, and to put the sights on G Gunner |
Bulletproof AR15 bolt
|
Bulletproof AR15 bolt
On Thu, 4 Oct 2007 15:35:05 -0500, "Randal O'Brian"
wrote: Is there any possibility of increasing the contact area of the lugs? I'm not familiar with the internal design of the AR-15. -- Ed Huntress It would require a redesign. the original .54" dia. bolt head has 7 radial lugs relatively evenly spaced (except for the extractor/feed rib gap) that are about .103" wide, .279" long, and .095" high. Total shear area is about 0.201 sq.in. Contact area is a little less than 0.068 sq. in. It locks by rotation into the barrel extension(screwed onto the barrel) So a heftier lock-up would entail a new bolt and extension which there probably is room for in a AR15 upper receiver. Randy Might be interesting to go with 3 larger locking lugs, or even 4. Gunner |
Bulletproof AR15 bolt
On Tue, 02 Oct 2007 22:24:26 -0500, JayCups
wrote: Hey Gunner, What comprises a California AR? What comes to mind is a single shot manual bolt with a 5' barrel, a flashing red warning light and GPS locator? Fixed 10 rd magazine. Or a magazine that requires tools to remove. Then all the evil pistol grips and stuff are ok as long as you have 3 or less. Straight pistol grip, muzzle brake . http://www.calguns.net/a_california_arak.htm https://www.vbd.com/noc/shop/product...CategoryID=102 https://www.vbd.com/noc/shop/product...&ProductID=239 http://www.fabten.com/online_catalog.htm Im thinking of something slightly different.... http://www.entreprise.com/CA_imb.htm Gunner Jay Cups, an exKalifornian now living in Texas Gunner Asch wrote: On Tue, 02 Oct 2007 01:04:38 -0000, trg-s338 wrote: If one were to build a bulletproof AR 15 bolt, meaning no cracking of lug shearing with automatic use and slow wear , what material would you make it out of? What treatment processes would you do attain this strength? trg-s338 Personally..Id buy one. They are cheap, and properly head treated and made of the proper materials. Im considering building a California AR, but will be using a commercial bolt. Gunner |
Bulletproof AR15 bolt
On Sun, 07 Oct 2007 01:46:28 -0700, Gunner Asch
wrote: On Thu, 4 Oct 2007 15:35:05 -0500, "Randal O'Brian" wrote: Is there any possibility of increasing the contact area of the lugs? I'm not familiar with the internal design of the AR-15. -- Ed Huntress It would require a redesign. the original .54" dia. bolt head has 7 radial lugs relatively evenly spaced (except for the extractor/feed rib gap) that are about .103" wide, .279" long, and .095" high. Total shear area is about 0.201 sq.in. Contact area is a little less than 0.068 sq. in. It locks by rotation into the barrel extension(screwed onto the barrel) So a heftier lock-up would entail a new bolt and extension which there probably is room for in a AR15 upper receiver. Randy Might be interesting to go with 3 larger locking lugs, or even 4. Gunner Won't work without redesigning the bolt carrier. the reason for the many locking lugs is to decrease the rotation necessary to unlock. Given that one of the design criteria for the AR-15 was light weight I would guess that the whole weapon was made as small and light as possible and likely the bolt just won't hold any more. I did a bit of research on the 6.5 and it is loaded to 42,000 psi while the permissible MAP for the AR15/M16 action is only 45,000 psi which isn't really a high pressure, all things considering. I don't suppose that the original poster will want to hear it but I suspect that the M-16 is just not the correct action to use for that particular cartridge. Bruce in Bangkok (brucepaigeATgmailDOTcom) |
Bulletproof AR15 bolt
|
Bulletproof AR15 bolt
On Sun, 07 Oct 2007 10:03:42 -0700, with neither quill nor qualm,
Gunner Asch quickly quoth: On Sun, 07 Oct 2007 16:21:11 +0700, wrote: I did a bit of research on the 6.5 and it is loaded to 42,000 psi while the permissible MAP for the AR15/M16 action is only 45,000 psi which isn't really a high pressure, all things considering. I don't suppose that the original poster will want to hear it but I suspect that the M-16 is just not the correct action to use for that particular cartridge. Bruce in Bangkok (brucepaigeATgmailDOTcom) 45,000 psi???? http://en.wikipedia.org/wiki/.223_Remington All my manuals say 52,000 +/- I believe they use metric psi in Thailand, Gunner. ;) -- Ultimately, the only power to which man should aspire is that which he exercises over himself. -- Elie Wiesel |
Bulletproof AR15 bolt
On Sun, 07 Oct 2007 10:03:42 -0700, Gunner Asch
wrote: On Sun, 07 Oct 2007 16:21:11 +0700, wrote: On Sun, 07 Oct 2007 01:46:28 -0700, Gunner Asch wrote: On Thu, 4 Oct 2007 15:35:05 -0500, "Randal O'Brian" wrote: Is there any possibility of increasing the contact area of the lugs? I'm not familiar with the internal design of the AR-15. -- Ed Huntress It would require a redesign. the original .54" dia. bolt head has 7 radial lugs relatively evenly spaced (except for the extractor/feed rib gap) that are about .103" wide, .279" long, and .095" high. Total shear area is about 0.201 sq.in. Contact area is a little less than 0.068 sq. in. It locks by rotation into the barrel extension(screwed onto the barrel) So a heftier lock-up would entail a new bolt and extension which there probably is room for in a AR15 upper receiver. Randy Might be interesting to go with 3 larger locking lugs, or even 4. Gunner Won't work without redesigning the bolt carrier. the reason for the many locking lugs is to decrease the rotation necessary to unlock. Given that one of the design criteria for the AR-15 was light weight I would guess that the whole weapon was made as small and light as possible and likely the bolt just won't hold any more. I did a bit of research on the 6.5 and it is loaded to 42,000 psi while the permissible MAP for the AR15/M16 action is only 45,000 psi which isn't really a high pressure, all things considering. I don't suppose that the original poster will want to hear it but I suspect that the M-16 is just not the correct action to use for that particular cartridge. Bruce in Bangkok (brucepaigeATgmailDOTcom) 45,000 psi???? http://en.wikipedia.org/wiki/.223_Remington All my manuals say 52,000 +/- Gunner You may be correct as my "research" was one article about the 6.5 & M-16. However the pressure was specified as "MAP" (which I have never seen before) rather then "CUP " which is the more common measurement. It may be that there is a conversion factor in there somewhere. It did seem pretty low as I commented. Bruce in Bangkok (brucepaigeATgmailDOTcom) |
Bulletproof AR15 bolt
On Oct 7, 6:13 pm, wrote:
On Sun, 07 Oct 2007 10:03:42 -0700, Gunner Asch wrote: On Sun, 07 Oct 2007 16:21:11 +0700, wrote: On Sun, 07 Oct 2007 01:46:28 -0700, Gunner Asch wrote: On Thu, 4 Oct 2007 15:35:05 -0500, "Randal O'Brian" wrote: Is there any possibility of increasing the contact area of the lugs? I'm not familiar with the internal design of the AR-15. -- Ed Huntress It would require a redesign. the original .54" dia. bolt head has 7 radial lugs relatively evenly spaced (except for the extractor/feed rib gap) that are about .103" wide, .279" long, and .095" high. Total shear area is about 0.201 sq.in. Contact area is a little less than 0.068 sq. in. It locks by rotation into the barrel extension(screwed onto the barrel) So a heftier lock-up would entail a new bolt and extension which there probably is room for in a AR15 upper receiver. Randy Might be interesting to go with 3 larger locking lugs, or even 4. Gunner Won't work without redesigning the bolt carrier. the reason for the many locking lugs is to decrease the rotation necessary to unlock. Given that one of the design criteria for the AR-15 was light weight I would guess that the whole weapon was made as small and light as possible and likely the bolt just won't hold any more. I did a bit of research on the 6.5 and it is loaded to 42,000 psi while the permissible MAP for the AR15/M16 action is only 45,000 psi which isn't really a high pressure, all things considering. I don't suppose that the original poster will want to hear it but I suspect that the M-16 is just not the correct action to use for that particular cartridge. Bruce in Bangkok (brucepaigeATgmailDOTcom) 45,000 psi???? http://en.wikipedia.org/wiki/.223_Remington All my manuals say 52,000 +/- Gunner You may be correct as my "research" was one article about the 6.5 & M-16. However the pressure was specified as "MAP" (which I have never seen before) rather then "CUP " which is the more common measurement. It may be that there is a conversion factor in there somewhere. It did seem pretty low as I commented. Bruce in Bangkok (brucepaigeATgmailDOTcom)- Hide quoted text - - Show quoted text - Metric pounds? Newtons per square inch? Mini-Average-Pascals? Might be pressures measured ala Brit practice, oiled case with the pressure measurement taken inline with the head. Even measuring radially, it makes a difference if the transducer is located in the chamber area or just ahead of the case mouth. Measurement methods have to be the same or comparisons are apples and oranges. Bolt failures aren't uncommon with wildcats that use bigger case heads in the AR platform, I believe this is one reason the Coast Guard quit using their near-.50 wildcats they bought for plunking boat engines on drug runners. The other problem is/was special operations guys using their M4s like they were light machine guns, I've seen several articles showing pictures where the barrels softened enough to put bullets out through the sides and the increased bolt velocity from the shorter barrels eventually did for the bolts. They didn't crack at the lugs, but broke at the camming slots. Takes dumping a LOT of ammo through the gun in short time, more than most grunts carry as a basic load. Lewis Machine has an "improved" bolt for those guys, might be worth looking at for the O.P. See Black Rifle II for more info. Stan |
Bulletproof AR15 bolt
On Oct 7, 2:21 am, wrote:
On Sun, 07 Oct 2007 01:46:28 -0700, Gunner Asch wrote: On Thu, 4 Oct 2007 15:35:05 -0500, "Randal O'Brian" wrote: Is there any possibility of increasing the contact area of the lugs? I'm not familiar with the internal design of the AR-15. -- Ed Huntress It would require a redesign. the original .54" dia. bolt head has 7 radial lugs relatively evenly spaced (except for the extractor/feed rib gap) that are about .103" wide, .279" long, and .095" high. Total shear area is about 0.201 sq.in. Contact area is a little less than 0.068 sq. in. It locks by rotation into the barrel extension(screwed onto the barrel) So a heftier lock-up would entail a new bolt and extension which there probably is room for in a AR15 upper receiver. Randy Might be interesting to go with 3 larger locking lugs, or even 4. Gunner Won't work without redesigning the bolt carrier. the reason for the many locking lugs is to decrease the rotation necessary to unlock. Given that one of the design criteria for the AR-15 was light weight I would guess that the whole weapon was made as small and light as possible and likely the bolt just won't hold any more. I did a bit of research on the 6.5 and it is loaded to 42,000 psi while the permissible MAP for the AR15/M16 action is only 45,000 psi which isn't really a high pressure, all things considering. I don't suppose that the original poster will want to hear it but I suspect that the M-16 is just not the correct action to use for that particular cartridge. Bruce in Bangkok (brucepaigeATgmailDOTcom) The cartridge was supposedly developed to give the M4 (M16 type) greater lethality via larger bullets, more energy and perhaps longer reach. This was to address the complaints of some in the "sandbox" that say in more than one occasion, the enemy just keeps on coming inspite of multi-hits with the .556 NATO round. In that respect, the design was intended for the M4 rifle just as the 6.8 SPC, another round developed for the M4. These two new cartridges were entered into a study commisioned and tested by the Army but so far have declined to adapt as replacement for the .556. The lack of total reliablity and/or performance is part of the reason I suspect. Getting back to the bolt, you may be right Bruce in that the M16 format is very limiting particularly in the mag well dimensions and the strength of the lockup mechanism. The use of a more powerful cartridge may indeed be too taxing to the design. Perhaps the only answer lies in the use of heavier .556 bullets say in the vicinity of 75 grains and hotter powders in order to achieve more lethality and power. As per discussion I've had privately with one poster, he argues that one only need look to NRA High Power or the National Match competitons to see the improvements those competetor have achieved. Perhaps the answer lies in their developement to technology. trg-s338 |
Bulletproof AR15 bolt
On Mon, 8 Oct 2007 08:15:16 -0400, "Ed Huntress"
wrote: "pyotr filipivich" wrote in message .. . After a Computer crash and the demise of civilization, it was learned Gunner Asch wrote on Sun, 07 Oct 2007 01:44:10 -0700 in rec.crafts.metalworking : As Bruce said..it would be worth while checking out impulse time /gas port pressure time and sampling size. Some piezo sensors on the gas block with comparisons with both the 5.56 and the Grendal, using loadings in the Grendal that appear to be bolt busters. Move the sensors down to the locking lug area of the barrel and check not only chamber pressure time/locking lug spikes, but the same on relocking. Its possible that relocking too fast could be an issue. Might need a softer spring and a buffer. Shrug Wish I had some time and hardware.... You just want a reason to shoot guns, and have someone else pick up the ammo bill. What's wrong with that? d8-) Reminds me of conversation some years ago, which went sideways into a discussion on how to set up a series of experiments to test some alleged effective sexual trivia. What's wrong with that? d8-) Damn...beat me to the above answers. "This is not a brouhahahaha! This is Science!" Ha. Have you ever read a technical article on terminal ballistics? That's goat abuse disguised as science. Hey! I wrote a few of those! Dont pass out all the secrets Gunner |
Bulletproof AR15 bolt
On Mon, 8 Oct 2007 09:42:11 -0500, "Randal O'Brian"
wrote: wrote in message oups.com... On Oct 7, 6:13 pm, wrote: On Sun, 07 Oct 2007 10:03:42 -0700, Gunner Asch wrote: On Sun, 07 Oct 2007 16:21:11 +0700, wrote: On Sun, 07 Oct 2007 01:46:28 -0700, Gunner Asch wrote: On Thu, 4 Oct 2007 15:35:05 -0500, "Randal O'Brian" wrote: Is there any possibility of increasing the contact area of the lugs? I'm not familiar with the internal design of the AR-15. -- Ed Huntress It would require a redesign. the original .54" dia. bolt head has 7 radial lugs relatively evenly spaced (except for the extractor/feed rib gap) that are about .103" wide, .279" long, and .095" high. Total shear area is about 0.201 sq.in. Contact area is a little less than 0.068 sq. in. It locks by rotation into the barrel extension(screwed onto the barrel) So a heftier lock-up would entail a new bolt and extension which there probably is room for in a AR15 upper receiver. Randy Might be interesting to go with 3 larger locking lugs, or even 4. Gunner Won't work without redesigning the bolt carrier. the reason for the many locking lugs is to decrease the rotation necessary to unlock. Given that one of the design criteria for the AR-15 was light weight I would guess that the whole weapon was made as small and light as possible and likely the bolt just won't hold any more. I did a bit of research on the 6.5 and it is loaded to 42,000 psi while the permissible MAP for the AR15/M16 action is only 45,000 psi which isn't really a high pressure, all things considering. I don't suppose that the original poster will want to hear it but I suspect that the M-16 is just not the correct action to use for that particular cartridge. Bruce in Bangkok (brucepaigeATgmailDOTcom) 45,000 psi???? http://en.wikipedia.org/wiki/.223_Remington All my manuals say 52,000 +/- Gunner You may be correct as my "research" was one article about the 6.5 & M-16. However the pressure was specified as "MAP" (which I have never seen before) rather then "CUP " which is the more common measurement. It may be that there is a conversion factor in there somewhere. It did seem pretty low as I commented. Bruce in Bangkok (brucepaigeATgmailDOTcom)- Hide quoted text - - Show quoted text - Metric pounds? Newtons per square inch? Mini-Average-Pascals? Might be pressures measured ala Brit practice, oiled case with the pressure measurement taken inline with the head. Even measuring radially, it makes a difference if the transducer is located in the chamber area or just ahead of the case mouth. Measurement methods have to be the same or comparisons are apples and oranges. Bolt failures aren't uncommon with wildcats that use bigger case heads in the AR platform, I believe this is one reason the Coast Guard quit using their near-.50 wildcats they bought for plunking boat engines on drug runners. The other problem is/was special operations guys using their M4s like they were light machine guns, I've seen several articles showing pictures where the barrels softened enough to put bullets out through the sides and the increased bolt velocity from the shorter barrels eventually did for the bolts. They didn't crack at the lugs, but broke at the camming slots. Takes dumping a LOT of ammo through the gun in short time, more than most grunts carry as a basic load. Lewis Machine has an "improved" bolt for those guys, might be worth looking at for the O.P. See Black Rifle II for more info. Stan MAP stands for Max. Average Pressure. in PSI. I believe the piezo pressure sensor is located at the case mouth, but I could be wrong. Randy You are correct. This of course brings up other considerations such as the effect of freebore, throat and lead etc. Gunner |
Bulletproof AR15 bolt
"Gunner Asch" wrote in message ... On Mon, 8 Oct 2007 08:15:16 -0400, "Ed Huntress" wrote: "pyotr filipivich" wrote in message . .. After a Computer crash and the demise of civilization, it was learned Gunner Asch wrote on Sun, 07 Oct 2007 01:44:10 -0700 in rec.crafts.metalworking : As Bruce said..it would be worth while checking out impulse time /gas port pressure time and sampling size. Some piezo sensors on the gas block with comparisons with both the 5.56 and the Grendal, using loadings in the Grendal that appear to be bolt busters. Move the sensors down to the locking lug area of the barrel and check not only chamber pressure time/locking lug spikes, but the same on relocking. Its possible that relocking too fast could be an issue. Might need a softer spring and a buffer. Shrug Wish I had some time and hardware.... You just want a reason to shoot guns, and have someone else pick up the ammo bill. What's wrong with that? d8-) Reminds me of conversation some years ago, which went sideways into a discussion on how to set up a series of experiments to test some alleged effective sexual trivia. What's wrong with that? d8-) Damn...beat me to the above answers. "This is not a brouhahahaha! This is Science!" Ha. Have you ever read a technical article on terminal ballistics? That's goat abuse disguised as science. Hey! I wrote a few of those! Dont pass out all the secrets I've always wondered about that: What do they do with the goats? I'd have to be really dedicated to sit there and shoot a tethered goat. For one thing, I only have one recipe for goat and I've never tried it. When I was a kid it was fun to shoot .22s into blocks of plasticine, however. -- Ed Huntress |
Bulletproof AR15 bolt
On Mon, 8 Oct 2007 13:57:03 -0400, "Ed Huntress"
wrote: "Gunner Asch" wrote in message .. . On Mon, 8 Oct 2007 08:15:16 -0400, "Ed Huntress" wrote: "pyotr filipivich" wrote in message ... After a Computer crash and the demise of civilization, it was learned Gunner Asch wrote on Sun, 07 Oct 2007 01:44:10 -0700 in rec.crafts.metalworking : As Bruce said..it would be worth while checking out impulse time /gas port pressure time and sampling size. Some piezo sensors on the gas block with comparisons with both the 5.56 and the Grendal, using loadings in the Grendal that appear to be bolt busters. Move the sensors down to the locking lug area of the barrel and check not only chamber pressure time/locking lug spikes, but the same on relocking. Its possible that relocking too fast could be an issue. Might need a softer spring and a buffer. Shrug Wish I had some time and hardware.... You just want a reason to shoot guns, and have someone else pick up the ammo bill. What's wrong with that? d8-) Reminds me of conversation some years ago, which went sideways into a discussion on how to set up a series of experiments to test some alleged effective sexual trivia. What's wrong with that? d8-) Damn...beat me to the above answers. "This is not a brouhahahaha! This is Science!" Ha. Have you ever read a technical article on terminal ballistics? That's goat abuse disguised as science. Hey! I wrote a few of those! Dont pass out all the secrets I've always wondered about that: What do they do with the goats? Its called Cabrito Asada. Yummmy!! I'd have to be really dedicated to sit there and shoot a tethered goat. For one thing, I only have one recipe for goat and I've never tried it. Google is your friend. When I was a kid it was fun to shoot .22s into blocks of plasticine, however. Ballistics gelletin is much better. Plasticine tends to "heal up" Gunner |
Bulletproof AR15 bolt
"Gunner Asch" wrote in message ... On Mon, 8 Oct 2007 13:57:03 -0400, "Ed Huntress" wrote: snip When I was a kid it was fun to shoot .22s into blocks of plasticine, however. Ballistics gelletin is much better. Plasticine tends to "heal up" Yeah, but at age 11, we didn't have no steenking ballistic gelatine. We had clay, and used woodchucks. -- Ed Huntress |
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