Is it okay to fire bullets that have too much crimp?

diowk · May 12, 2009, 04:06 AM

after about my first 100 rounds I realized that I didnt have my crimp die adjusted properly. Im reloading 45 acp. The first batch has a crimp of 0.469-0.471 the crimp is supposed to be 0.473 according to both my manuals. My new batch is all crimped to 0.473 but Im wondering if its okay to fire the other bullets or If I have to redo all of them. What could one expect from firing a bullet that has a crimp 0.004 " below manual stats? Im pretty sure I read that too much crimp on 45 acp can cause headspace problems but I dont know what that means. How much extra crimp would it take to cause "headspace problems"?

Sport45 · May 12, 2009, 04:11 AM

Fire away! 0.469" is a fairly standard crimp dimension for the cartridge in question.

diowk · May 12, 2009, 04:24 AM

thank you!!!!!

czfonz · May 12, 2009, 03:50 PM

how do you measure crimp?

L'derry · May 12, 2009, 05:07 PM

Quote:

how do you measure crimp?

Good question! I'd like to know as well.

stang46gt · May 12, 2009, 06:25 PM

I would/did measure crimp by measuring the middle of the case then measure at the crimp and subtract one from the other. I heard .002 - .003 is sufficient.

Tex S · May 12, 2009, 06:51 PM

I too have always wondered how to measure crimp. I have a dial caliper and a micrometer, but can't seem to get any kind of useable measurement using either. The area that is crimped is just too small.

Whats the trick?

Sport45 · May 12, 2009, 08:22 PM

I just measure case diameter at the mouth with a dial caliper. This works for taper crip. Revolver and rifle rounds that use a roll crimp can only be judged visually AFAIK.

F. Guffey · May 13, 2009, 11:21 AM

I am not the first, I have trouble with hand loads with A 45 ACP, reloads that look like the case swallowed a bullet will not feed, the only ammo it likes is new factory ammo, or ammo that looks and measures the same as new factory ammo, the perfect case is a sized case, seating a bullet can change that, on that one pistol I tapper crimp, then run the cases back threw the full length sizer die far enough to remove the bullet bulge, it is something like sizing/crimping/partial full length sizing. I am of the opinion over crimping is not possible unless the crimp portion of the die has a progressive tapper, and Richard Lee says the crimp makes the powder burn more efficiently and the amount of pressure required to expand the mouth of the case for bullet release is fixed, the bullet can start moving when the pressure reaches 200 psi or the bullet travel can be delayed with a crimp. Mr. Lee thought delaying the bullet gave the powder more time to to start burning, something like increasing efficiency with compression to concentrate heat.

F. Guffey

Dingoboyx · May 13, 2009, 11:30 AM

If the crimp is uniform and in the canalure (or behind the ridge) and you can't turn the projectile in the case (with alot of force using your fingers) I concider it to be a good crimp.

On the other hand, if you are firing a revolver, and the projectiles of the other 5 fall out on the floor/bench in front of you

when you fire the first shot, this could be an indication the crimp isn't quite tight enough

The down side of excessive crimping, is that it is hard on the case mouth, shortens the life of the brass.... not good. However, I don't think a hand lever operated press would be able to exert enough force on the crimp without damaging the case, to let you know you had crimed too hard (that or your reloading table would fall over as you sat on the press's arm)

May 12, 2009, 04:06 AM	#1
diowk Member Join Date: April 19, 2009 Posts: 31	Is it okay to fire bullets that have too much crimp? after about my first 100 rounds I realized that I didnt have my crimp die adjusted properly. Im reloading 45 acp. The first batch has a crimp of 0.469-0.471 the crimp is supposed to be 0.473 according to both my manuals. My new batch is all crimped to 0.473 but Im wondering if its okay to fire the other bullets or If I have to redo all of them. What could one expect from firing a bullet that has a crimp 0.004 " below manual stats? Im pretty sure I read that too much crimp on 45 acp can cause headspace problems but I dont know what that means. How much extra crimp would it take to cause "headspace problems"?

May 12, 2009, 04:11 AM	#2
Sport45 Senior Member Join Date: May 25, 1999 Location: Too close to Houston Posts: 4,196	Fire away! 0.469" is a fairly standard crimp dimension for the cartridge in question. __________________ Proud member of the NRA and Texas State Rifle Association. Registered and active voter.

May 12, 2009, 06:25 PM	#6
stang46gt Member Join Date: August 24, 2005 Posts: 84	Though I just started reloading I would/did measure crimp by measuring the middle of the case then measure at the crimp and subtract one from the other. I heard .002 - .003 is sufficient.

May 12, 2009, 08:22 PM	#8
Sport45 Senior Member Join Date: May 25, 1999 Location: Too close to Houston Posts: 4,196	I just measure case diameter at the mouth with a dial caliper. This works for taper crip. Revolver and rifle rounds that use a roll crimp can only be judged visually AFAIK. __________________ Proud member of the NRA and Texas State Rifle Association. Registered and active voter.

May 13, 2009, 11:30 AM	#10
Dingoboyx Senior Member Join Date: March 7, 2009 Location: South East Queensland, Australia Posts: 1,513	I just look at them If the crimp is uniform and in the canalure (or behind the ridge) and you can't turn the projectile in the case (with alot of force using your fingers) I concider it to be a good crimp. On the other hand, if you are firing a revolver, and the projectiles of the other 5 fall out on the floor/bench in front of you when you fire the first shot, this could be an indication the crimp isn't quite tight enough The down side of excessive crimping, is that it is hard on the case mouth, shortens the life of the brass.... not good. However, I don't think a hand lever operated press would be able to exert enough force on the crimp without damaging the case, to let you know you had crimed too hard (that or your reloading table would fall over as you sat on the press's arm) __________________ Muzza If you cant blind them with brilliance, Baffle them with BS Be alert...... there is a shortage of LERTs

May 12, 2009, 04:24 AM	#3
diowk Member Join Date: April 19, 2009 Posts: 31	thank you!!!!!

May 12, 2009, 03:50 PM	#4
czfonz Member Join Date: April 29, 2009 Location: IL Posts: 46	how do you measure crimp?

May 12, 2009, 06:51 PM	#7
Tex S Senior Member Join Date: November 12, 2008 Location: Fort Worth, TEXAS Posts: 909	I too have always wondered how to measure crimp. I have a dial caliper and a micrometer, but can't seem to get any kind of useable measurement using either. The area that is crimped is just too small. Whats the trick?

May 13, 2009, 11:21 AM	#9
F. Guffey Senior Member Join Date: July 18, 2008 Posts: 7,249	I am not the first, I have trouble with hand loads with A 45 ACP, reloads that look like the case swallowed a bullet will not feed, the only ammo it likes is new factory ammo, or ammo that looks and measures the same as new factory ammo, the perfect case is a sized case, seating a bullet can change that, on that one pistol I tapper crimp, then run the cases back threw the full length sizer die far enough to remove the bullet bulge, it is something like sizing/crimping/partial full length sizing. I am of the opinion over crimping is not possible unless the crimp portion of the die has a progressive tapper, and Richard Lee says the crimp makes the powder burn more efficiently and the amount of pressure required to expand the mouth of the case for bullet release is fixed, the bullet can start moving when the pressure reaches 200 psi or the bullet travel can be delayed with a crimp. Mr. Lee thought delaying the bullet gave the powder more time to to start burning, something like increasing efficiency with compression to concentrate heat. F. Guffey