On Fri, 6 Sep 2013 13:08:37 -0500, "Paul K. Dickman"
wrote:


"pyotr filipivich" wrote in message
.. .
Greetings

I have a couple questions on bullet sizes and barrel thickness.

In order to keep my hand in over summer break, I'm in the midst of
a CAD project. Maybe I can learn a few things too, about CAD, Catia
and the object of my project.
Yes, for "grins and giggles", I am attempting to gin up drawings
for the 6.35 mm "Pistola Con Caricato". The three barrel 18 shot one
off from the 1920's. Yeah, that one.
So, I have the SAAMI pdf with the dimension of the standard .25
cal / 6.35x16mmSR Browning cartridge. "Way cool" - but it did cause a
bit of "redrawing" as I had made preliminary drawings with a dimension
of 6.35 mm. "oops" (Actually, I was trying to get the geometry
sorted out, how to get lines to start where I wanted them, instead of
the apparent random location the program defaults to.)
Anyway, I now have a nice profile of a standard 6.36x16mmSR round
- bullet and cartridge. [23.11 mm OAL, as per spec]. What I don't
know however is: how long is the bullet itself?
"As Drawn" the bullet has nothing inside the brass to hold it
together. While this may not be a serious problem for merely drafting
a chamber for the cartridge, it offends my Professional Standards to
not have a "real bullet" correctly sized which can then be matched up
with the cartridge, and then that Assembly inserted into the Cylinder
Unit.

So, my questions:
1) Does anyone have the specs for the bullets themselves? Or a
link to where those same specs can be found?

2) Barrel dimensions. I have learned so far that the 25ACP is a
"low power" round, so barrel thickness is not a serious matter. I'm
guesstimating from the half dozen available photos somewhere around 2
to 3 mm thickness, which gives a diameter of 10.35 to 11.35 mm, if
based off the bullet diameter, 11 to 13 mm if base off the cartridge
diameter.
[FWI, I have set this up with the semi-deranged idea that I can
change a few constants and viola - scale it up to .38, 38 Special,
357, 40 S&W or 45 ACP. Or down to a .22 short. Or whatever. [.600
Nitro Express? .50 BMG?]

So, I need a formula of some sort, or a reference chart, that will
provide me with some kind of ball park figure for the actual barrel
thickness ( radius of the out side of the barrel minus the bore
radius). As in "If you were going to bore a hole the length of a steel
round to serve as a barrel, what radius/diameter round would you
need?"
(As I sit here, I realize I can start by boring a hole in a 6 inch
cube, then turn the cube down concentric to the axis, until I get a
barrel radius of the size I want. But that size is also determined by
the strength of the material, the pressure in the chamber, intended
amount felt recoil, and so forth. But I don't know what outside
diameter should be. (Yeah, I know - "About that much, plus or minus a
quart...")

So, does anyone have ballpark figures for determining barrel
dimensions, based upon the size bullet / cartridge it is to fire? Part
of me thinks even an "X is safe, plus a safety margin of Y%" would
work. At least for a "proof of concept" silliness.

I think I am going to have to take that class on materials
properties.


tschus
pyotr

--
pyotr filipivich.
Discussing the decline in the US's tech edge, James Niccol once wrote
"It used to be that the USA was pretty good at producing stuff teenaged
boys could lose a finger or two playing with."

These guys will yammer on forever about how to get an answer but no one will
do it.
I just pulled one apart.

The bullet is .445 in long.
it was imbedded .155 in into the case mouth.
The ogive starts just forward of the embedment.
Standard factory FMJ 50gr

Paul K. Dickman

So you actually HAD one. Good lad! I gave all the poodle shooter
stuff away years ago when I sold the last Baby Browning.


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