45 ACP crimp and bullet deformation

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a__l__a__n

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I've been reloading various calibers for years but am just beginning to reload 45 ACP. I've ordered bullets from precisionbullets.com (free shipping!) which are advertised as 0.4515 diameter. I've measured case rim diameter at 0.012, so the no-crimp diameter (only flare removed) would be 0.4755. However, there is a nice video explanation of crimping on their site which advises starting at 0.468 - 0.469"

https://precisionbullets.com/2019/08/03/bullet-crimping/

It seems to me that such a tight crimp would necessarily deform the bullet - which I've always heard was a bad thing.

While waiting for my bullets to arrive, I've pulled a few various bullets from commercial ammo after measuring the OAL. Then I reassembled them without powder & primer to test cycling in my 1911 at various OAL for each bullet style. I've discovered that I need at least 0.468 crimp on these bullets to prevent bullet setback during cycling. But when I pull a bullet after giving it a 0.468 crimp, the bullet has a crimp dent.

Maybe I should just follow the advice on the video and not worry about the deformed bullets.

Am I missing something?
Thanks in advance for your insights.
 
I've discovered that I need at least 0.468 crimp on these bullets to prevent bullet setback during cycling. But when I pull a bullet after giving it a 0.468 crimp, the bullet has a crimp dent.

Auto pistol ammo, unlike revolver ammo, does not rely on the crimp to hold the bullet, it uses neck tension. All the crimp does in auto ammo is remove the flare. If you are getting bullet setback you probably are using too much flare or your sizing die is not sizing correctly. Some brands of brass because of their thin sidewalls, can also contribute to setback issues. The commercial ammo your are pulling may be using an after seating resizing die like Lee's FCD to assure consistent feeding and this may be what is giving the crease in the bullet. Small deformations will not greatly impact on ammo, especially in handgun ammo used at short distances. Too much crimp can actually reduce neck tension and contribute to bullet setback, so I always flare my auto cases as minimally as possible. Excessive crimp/bullet deformation is more of a issue with cheaper plated bullets because of their construction as opposed to regular jacketed or cast bullets.
 
45acp brass has a wide variety of case thickness and case springiness traits. If you’re loading jacketed or plated bullets, there’s a good chance that, unless you have a smaller-than-saami-standard sizing die, you’ll get setback with some headstamps.

For instance, nothing I do makes R-P brass not setback with jacketed bullets short of misusing crimp to the point of deforming bullets. I save it for rounds for 45 ACP revolvers.

See whether particular headstamps are giving you the setback woes. You may need to start sorting by headstamps, or at least picking out the thin and unspringy ones.
 
I have been shooting Bullseye Pistol for around five years, this year I was talking to "Ernest", a Master Class shooter about the powder he used, the bullets he used, and the crimp he used. Ernest had some bragging targets with him, and I took pictures of them,

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Two of the targets were shot in competition and one was shot during load development. Ernest gave me a round and a bullet, and I measured the crimp on that round and it was 0.469" at the case mouth. Yes this will put a crimp groove in a bullet that does not have a crimp groove. It also shoots fine. I don't shoot this well, and there are few that do. I have not tried not crimping, just removing the bell, because I believe it will cause misfeeds and function is important to me. I want my pistols to feed and extract.
 
I may not have as much knowledge and technical experience as some here, but I do have a few years experience reloading semi-auto rounds (and I slept at a Motel 6 last night). I have 6 semi-auto handguns and one pistol caliber carbine, and I quit measuring crimp many years ago. I use a taper crimp die to remove the excess flare only as I rely on neck tension to keep the bullets in place (swaged, cast jacketed,and PCed bullets). When I'm working up a load I'll sort brass by headstamp and once I have developed a good load I often switch to mixed cases. When I started reloading for my first semi-auto round I was concerned about setback, mainly because I paid too much attention to internet wisdom, and now I just deflare and plunk test for my 380 Autos, 9mms and 45 ACPs. I started reloading for my first centerfire semi-auto in '87 and cannot say I have ever had a bullet setback...
 
I crimp my 45 acp to 0.470"-0.471". I sort out ALL RP brass for it's know to be thinner and softer, requires a specific expander. It can be used with over sized lead but not jacketed without changing to a different size expander (smaller). So I just throw all my RP brass in a separate box.
 
And maybe your COAL is too long causing the bullet to bump the lands of the rifling. This could cause bullet setback.

If I cycle the same loaded rounds numerous times (including factory ammo) I will eventually get bullet setback.
 
DB9A7C50-2355-475E-B50B-2ED44EDEC55C.jpeg I just started loading 45acp myself. I cast the bullets last night and loaded 50 for today’s range trip. I can honestly say I’ve never measured crimp diameter because I’ve never heard of it. I loaded to OAL and nothing more. Not one of these rounds had a malfunction. I’m using a Lee three die set, no FCD.
 
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And maybe your COAL is too long causing the bullet to bump the lands of the rifling. This could cause bullet setback.

If I cycle the same loaded rounds numerous times (including factory ammo) I will eventually get bullet setback.
If this were the case, wouldn’t he have an issue with rounds fitting in the magazine?
 
So I just throw all my RP brass in a separate box.
That's what I do with all my R-P brass too (9mm , .38Spl, and .45ACP). I usually end up giving it away

I can honestly say I’ve never measured crimp diameter because I’ve never heard of it.
I didn't either, until I talked to a dyed-in-the-wool .45ACP shooter.

He not only measured his crimp, but he had a Redding Micrometer Adjustable Crimping Die with which to adjust it...which I guess shouldn't have been surprising as it was part of his set which included a Dual Ring Carbide Sizing Die and a Competition Bullet Seating Die
 
I have been shooting Bullseye Pistol for around five years, this year I was talking to "Ernest", a Master Class shooter about the powder he used, the bullets he used, and the crimp he used. Ernest had some bragging targets with him, and I took pictures of them,

View attachment 863661
View attachment 863662


View attachment 863663


Two of the targets were shot in competition and one was shot during load development. Ernest gave me a round and a bullet, and I measured the crimp on that round and it was 0.469" at the case mouth. Yes this will put a crimp groove in a bullet that does not have a crimp groove. It also shoots fine. I don't shoot this well, and there are few that do. I have not tried not crimping, just removing the bell, because I believe it will cause misfeeds and function is important to me. I want my pistols to feed and extract.

That's some impressive shooting. So a crimp groove in the bullet doesn't necessarily hurt performance. Crimping as Precision Bullets recommends will put a crimp groove in the bullet but it probably will still shoot fine.

If you load a round with only neck tension holding the bullet in place, and then stick it in your magazine and shoot it, it's probably going to be fine. If you repeatedly chamber and eject the round, it is likely to experience setback. That's what I've experienced.

BTW when I loaded the dummy rounds, I separately adjusted the dies to every case. I measured each round to within .001" of the OAL I was seeking for that particular bullet and I measured the crimp diameter on every bullet. After loading, pulling, and reloading several times, I determined that 0.468" works best for holding these bullets against setback. But of course they had been loaded several times and had crimp grooves from previous loadings.
 
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45acp brass has a wide variety of case thickness and case springiness traits. If you’re loading jacketed or plated bullets, there’s a good chance that, unless you have a smaller-than-saami-standard sizing die, you’ll get setback with some headstamps.

For instance, nothing I do makes R-P brass not setback with jacketed bullets short of misusing crimp to the point of deforming bullets. I save it for rounds for 45 ACP revolvers.

See whether particular headstamps are giving you the setback woes. You may need to start sorting by headstamps, or at least picking out the thin and unspringy ones.

I actually do sort by headstamp when I reload. Sometimes I even measure all the case lengths. Yes, it takes me a while to load 100 rounds.
 
From NRA reprint. 1950 or 60's The taper crimp was applied by running the loaded round back into the old steel sizing die. This worked because the dies had a taper . THIS WILL NOT WORK WITH THE NEWER CARBIDE DIES. The roll crimp should be used only in revolvers. Imo. full.jpg Why i buy Starline brass for accuracy. It takes 45 to over 100 pounds to move bullet using different brands of brass. (Range brass) full.jpg
I find just removing the bell and applying just enough taper crimp so rounds chamber, works for me, an old Bullseye shooter.
Starline brass, WLP, 3.8grs Bullseye powder, home cast Lyman 200 gr BB bullets. Hard alloy. Near pure lead caused feeding problems. A good gun will produce 3" groups @ 50 yards from a rest.

full.jpg
 
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That's some impressive shooting. So a crimp groove in the bullet doesn't necessarily hurt performance. Crimping as Precision Bullets recommends will put a crimp groove in the bullet but it probably will still shoot fine.

Putting a crimp in a pistol bullet does not seem to affect accuracy, at least out to 50 yards. Now if you shot that round in a rifle, you might see something. It is known that crimping rifle bullets is bad.

This:

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Will do this:

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But that is in the noise level for a hand held pistol.
 
When setting up my seat- crimp .45 acp die I try for a .470 crimp, but up to .471 will pass the plunk test in my Springfield.I also find R P .45 acp brass to be thin walled, and needs a .469 crimp for a good hold. hdbiker
 
Hmm... I take range brass, clean it, dump it in the collator and load it. It all gets crimped to .471".

Since I shoot defensive pistol matches it's good enough for me. On a good day I can make one ragged hole at 20 yards.
 
If this were the case, wouldn’t he have an issue with rounds fitting in the magazine?

Bullet set back means the rounds are getting shorter either due to repeated cycling or recoil. Never had an issue with bullet set back due to recoil but have experienced bullet set back from repeated cycling.

Repeated cycling, in my case, is changing mags in the same gun repeatedly when changing back and forth from range ammo to SD ammo. The more times I change and chamber the same rounds the greater the risk of set back.

As the COAL becomes shorter, due to the set back, the rounds become easier to fit in the magazines.
 
“And maybe your COAL is too long causing the bullet to bump the lands of the rifling. This could cause bullet setback.”
This is the statement in question.
 
I'm thinking it has more to do with hitting the ramp and/or the rim of the chamber (in my situation). All of these rounds are 1.260" OAL or below and all appear to be head spacing on the rim.
 
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