is it possible to taper crimp a .45acp cartridge so much that the round moves forward in the chamber so much that the firing pin doesn't reach the primer enough to fire the round ?
.45acp Crimping
- Thread starter jimmyj
- Start date
Register to hide this ad
AJ
US Veteran
Anything is possible..........but have never seen it......yet. I taper crimp all my .45 ACP that is used in my 1911's and 625.
Stay safe over there!
I suspect if you over crimped THAT much, the cartridge would get so misshapen that it would resist or refuse to chamber entirely. If it were out of battery, the firing pin would not be allowed to hit it.
I believe it was John Giles that developed the very idea of the taper crimp as opposed to a roll crimp. He was adamant that his preferred crimp on a 200gr LSWC in .45 Auto for pure Bullseye competition accuracy should read 0.469”.
I believe it was John Giles that developed the very idea of the taper crimp as opposed to a roll crimp. He was adamant that his preferred crimp on a 200gr LSWC in .45 Auto for pure Bullseye competition accuracy should read 0.469”.
STORMINORMAN
Member
Unless one (OVER!)expands the case mouth to a funnel shape, how could a taper crimp move the bullet forward at all...?
Cheers!
Cheers!
Yes it's possible if the cases are too short. The round headspaces on the case mouth. I.E. If you have a max length chamber, cases are below minimum spec in length and you have the correct crimp .469-.470 I assume it would be possible to have miss fires but not because the bullet moved forward but that the rounds are too short. The case rim should be flush to a couple of thousands shy of the barrel hood. If they are severely over crimped, as Sevens has stated they most likely would not chamber. Will they pass the "plunk" test? Are they below the hood?
If you follow a lot of info on bullseye shooting you will see crimps for lead swc as tight as .463. I use .464-.465 for mine. If you see some of the photos of the groups shot with Giles pistols his groups are less than 2 inches at 50 yards with a .463 crimp on a lead swc. All taper crimps.
Beemer-mark
Member
Put the bullet in the brass and before crimping try to physically force the bullet deeper. Not possible. If the loaded cartridge is the correct length a taper crimp is all you need.
FWIW:
In 2021 I was bord, so I did a little testing with 9mm brass in a 1911 bbl chambered in 9mm.
A .374" crimp.
The .374" crimp plunk test
A .365" crimp.
The .365" crimp plunk test.
Both cases started out being the same length. After taper crimping the
.374" crimped case was .750" long
.365" crimped cases was .748" long
The .374" crimp excessive & the .365" crimp is extreme. Both still plunked/functioned/fired in that 1911/9mm.
In 2021 I was bord, so I did a little testing with 9mm brass in a 1911 bbl chambered in 9mm.
A .374" crimp.
The .374" crimp plunk test
A .365" crimp.
The .365" crimp plunk test.
Both cases started out being the same length. After taper crimping the
.374" crimped case was .750" long
.365" crimped cases was .748" long
The .374" crimp excessive & the .365" crimp is extreme. Both still plunked/functioned/fired in that 1911/9mm.
What have you done Jimmy?
You took the words right out of my mouth.
