On Mon, 11 Apr 2016 09:11:57 -0700, wrote:

On Mon, 11 Apr 2016 11:26:50 -0400, Neon John wrote:

On Wed, 06 Apr 2016 09:03:34 -0700, wrote:


Cases are usually crimped to hold the bullet tightly. If you don't
crimp the bullet then the cartridges will have to be handled a bit
more carefully and probably should only be used in a single shot
weapon.

No, not necessarily. Before my eyes went, I was a very serious
Metallic Silhouette shooter. I have a custom-built bolt action
handgun with a 14" barrel and chambered for .308.

Needless to say the recoil is brutal. I would never ever crimp a
case! The release pressure is so unreliable that accuracy would
suffer badly. With carefully head-spaced and neck-turned brass, the
bullet can be very tightly and very repeatably retained by slight
swaging during seating.

I know standard rimfire .22s have crimped cases and need to in order
for the correct pressure build up.

I don't think so. The crimp is strictly for bullet retention since
the bullet extends into the case only enough for the crimp groove.

Since you're making the rifle and the cartridges, you can do like a
lot of bench-rest shooters do and what I did. I head-spaced the
chamber so that when the cartridge was inserted and the bolt closed,
the bullet was resting on the beginning of the rifling.

Using this method, the bullet has no jump from starting to exit the
cartridge until it encounters the rifling. That little jump can let
the bullet enter the rifling slightly cocked which affects accuracy.

There was a normal headspace shoulder a few thousands forward to catch
a short cartridge which includes SAAMI spec commercial cartridges.

In your case, the case would necessarily have to be swaged pretty
tightly to resist the force of the firing pin. I anticipate many
misfires. I'm not sure why you're deviating from the tried and true
rim on your wildcat.

John


John DeArmond
http://www.neon-john.com
http://www.tnduction.com
Tellico Plains, Occupied TN
See website for email address
I'm not sure either. At this point I am just thinking about what would
be required for a rimless cartridge and if it would be worth the
effort. Timewise it would seem to be a waste but I like making things,
especially out of metal, and I like shooting. Having a machine shop
and being a machinist makes it easier to make things. All the comments
posted so far relating to my first post have been a good education.
Eric

I mentioned earlier that .22 rimfires have ground glass in the primer
and that they rely on the crimp to build up pressure. Or they did, 30
or 40 years ago, when I learned those things.

Wondering if they still use the glass, and what the current thinking
is on crimping rimfire cartridges, I came across this informative
piece from _American Rifleman_:

http://www.americanrifleman.org/arti...le-22-rimfire/

Maybe this will add to your store of knowledge. The story on crimping
centerfires is full of arguments and opinions, but this is the
clearest piece I've seen on rimfires.

--
Ed Huntress