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Old May 21, 2020, 01:30 PM   #1
seanc
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.45ACP bullet setback

What's an allowable setback for .45ACP?

I'm new to reloading .45ACP and 3-die set vs. 4-die sets for other calibers with a separate crimp die. I loaded a dummy round (200 gn FP) and re-chambered it several times. Initial COAL was 1.199". After 6 chamberings, it only dropped to 1.197. The 7th went to 1.195 and I think is still good. The 8th dropped to 1.193" and that's when I thought it might be compressed too much and stopped the experiment there (and pulled the bullet because I'm a cheap bastard).

The 1.199" was derived from plunk testing. I think I'm good with the seater/crimper combo after this test, at least for 7 re-chamberings. This is only for my practice ammo so these probably won't be re-chambered too often, certainly not 7/8 times before being shot. I'm just wondering what a serious setback is for 45.
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Old May 21, 2020, 01:49 PM   #2
Jim Watson
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Setback visible to the naked eye is my cutoff.
The only thing I chamber repeatedly is the hideout gun I carry hollow points in and practice with reloads or the cheap stuff.
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Old May 21, 2020, 02:12 PM   #3
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What's an allowable setback for .45ACP?
TO me, that would be ZERO.
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Old May 21, 2020, 03:33 PM   #4
74A95
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Setback is common for some pistols depending on the angle the rounds hits the feed ramp. Of the factory 45 rounds I've measured, 75% of them had setback during one cycle when feeding from a 1911. The average of those had 0.011" setback.

You're getting .006" from 8 chamberings. Wow! People should be begging you for your secret to having so little setback!

I ran some quick numbers through QuickLOAD for a lead bullet, 200 grain at 1.199" with 6.5 grains of Unique. Pressure was 16,068 psi.

Seating it to 1.193" raised pressure by 351 psi to 16,419.

BOTTOM LINE: You're fine. Your gun will never notice a 351 psi pressure increase. That's probably within the range of normal pressure variance when using the same charge weight.

How much setback is required before you start worrying? That probably depends on the bullet, its seated OAL and the powder charge. You would probably need to have your load near maximum pressure and then see pressure rise over the +P limit for 45 ACP (23,000) since most guns can handle that.

In your example, you have nothing to worry about.
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Old May 21, 2020, 03:43 PM   #5
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Agree with 74A95, especially if you are using a lower pressure loading to start with. Can not imagine how i would end up chambering a practice load more than twice. Once did a test of setback years back with factory 45 acp defense loads. If memory holds, only one brand had less than .003 on one loading from slide lock back using the slide release. Things have improved since then.

When loading plus p velocity defense rounds with jacketed bullets, am like 44 AMP in preferring no setback and it can be done with right brass/bullet combo.
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Old May 21, 2020, 03:53 PM   #6
seanc
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Thanks 74A95.

I forgot to mention the powder/load: 4.2 gn of Clays.

I'm not maxed out, but Clays ramps up quickly. Since I haven't used a seater/crimper before, I wanted to see how much of a crimp it gives vs a separate crimper die, and obviously, for 45, I don't want a heavy crimp either. These are just paper punching rounds. I just picked up a low millage Glock 30S, which are rated for +P, so the gun should handle it even if there was a mild pressure spike. Rounds should only get 1 pass through the chambering process.
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Old May 21, 2020, 03:59 PM   #7
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Quote:
Once did a test of setback years back with factory 45 acp defense loads. If memory holds, only one brand had less than .003 on one loading from slide lock back using the slide release. Things have improved since then.
Zeke:
I was just checking my 9mm factory JHP carry ammo and found one of those rounds with significant setback. I banged it out just enough and then seated to the correct length and then crimped it. I'll be shooting that round tomorrow. I agree, I don't want to see ANY setback in carry ammo, even for 9mm standard pressure. I don't know how many times that round was rechambered before it got setback, but it makes me wonder about HST rounds and how tight they're crimped.
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Old May 21, 2020, 10:12 PM   #8
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Rounds should only get 1 pass through the chambering process.
Spoken like a true ammunition salesman!

I hold that setback should not happen. I think that its more common today than it was in the past, and the general attitude that "setback happens" and as long as its not "too much" its ok is why it happens more often today.

I suppose "modern" guns are designed to produce setback, I can't say. What I do say is that I've read extensively, books and magazine articles from the late 1940s on up, and have been loading since the early 70s.

Setback is rarely mentioned, and only in the context of faulty rounds. You do not find any mention of bullet setback being a common thing let alone an expected thing in the literature of the 40s, 50s, 60s, or 70s.

IF setback had been a common thing in those days, I would expect it to be something common in the literature of the day.

Next, I don't believe setback is inevitable, based on real world observation. I have personally seen factory ammo, Federal 185gr JHP, that was kept as "defense ammo" from its purchase in 1980 until it was finally replaced about 2002. One mag full of this stuff, chambered and rechambered HUNDREDS of times, at least. Chambered so many times the nickel cases has brass stripes where the nickel had worn off. I got to check them for length, frequently. NO SETBACK, not any. Bullets never moved at all. Gun was a SiG P220.

And btw that ammo, chambered over and over and over, which never got any setback, fired exactly the same, and to the same point of aim as it did when new in 1980.

I've made ammo that I've chambered dozens of times (at least) without any setback. I think the attitude that its good enough as long as it works once, has resulted in ammo that does just that.

I'm not suggesting any kind of collusion, conspiracy, or grand master plan among the ammo companies, I just think that they used to make their ammo the best they possibly could, and now make it "good enough"

Of course, I could be wrong, but my opinion fits the results I've observed.

I believe that if you get setback from chambering a round, something wasn't done, or done right "enough".
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Old May 21, 2020, 10:46 PM   #9
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I don't like to see any setback. But I will tolerate 'some' for lower pressure cartridges.

I would not waste a second of my day worrying about less than 10 thou. COAL deviations caused by bullet variation can be that large with some bullets.

Because I've recently been messing with a Mauser rifle converted to .45 Auto, and it is very prone to causing notable setback if it mis-feeds, I spent some time running the numbers in QuickLoad - for 185 gr Berry's HBRNs, 185 gr XTPs, and generic 230 FMJs, with a couple different powders.

I found that I could not seat the bullets deep enough (via setback) to exceed 58k psi. That is actually acceptable in the rifle (for an over-pressure that's likely to pierce primers). It would be very bad in a handgun, but probably not 'destroy the handgun' bad. It is bad and unwanted, but far better than a double charge of a fast powder. (Which are typically in the realm of 95k psi and up.)
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Old May 21, 2020, 11:18 PM   #10
74A95
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Quote:
Originally Posted by 44 AMP View Post
I think that its more common today than it was in the past,
This requires evidence. Please present it.


Quote:
Originally Posted by 44 AMP View Post

I suppose "modern" guns are designed to produce setback, I can't say.
Umm, what? You must be kidding. I'm sure gun designers sit around a table and won't give the approval for their new design until they have proof that it will produce setback. Get real!

The 1911 is a big offender with respect to setback. Each round from the magazine feeds at a different angle, and the rounds from a full magazine nosedive the most, hit the feed ramp at a sharper angle, and likely produce the most setback. Let's see, the 1911 has been around since . . . 1911. So, yeah, if your definition of 'modern' includes guns designed in the last 110 years, it qualifies.


Quote:
Originally Posted by 44 AMP View Post
What I do say is that I've read extensively, books and magazine articles from the late 1940s on up, and have been loading since the early 70s.

Setback is rarely mentioned, and only in the context of faulty rounds. You do not find any mention of bullet setback being a common thing let alone an expected thing in the literature of the 40s, 50s, 60s, or 70s.

IF setback had been a common thing in those days, I would expect it to be something common in the literature of the day.

Maybe it isn't mentioned in articles because it isn't germane to the goal of the article. Even with ammo reviews the focus is on reliability, velocity and accuracy. Maybe it happened and they ignored it. Maybe it happened and they didn't know it because to identify setback you have to measure the round before and after it has feed into the chamber. How many reviewer do that when they're testing ammo? I strongly suspect that's mighty rare because when they test fire ammo, it if feeds, they shoot it! Setback might have occurred with every round, but it's hard to know if you just did your job and pulled the trigger.

The absence of it being mentioned does not mean it didn't happen. I don't think gunwriters have a 'measure every round for setback' order as part of their instructions from editors.

I can see it being mentioned in the case of faulty rounds but in those instances we're generally referring to massive amounts of setback, clearly visible to the naked eye, often producing a malfunction. These are not generally rounds suffering .005', .010" and other small amounts that are generally only detected by actually measuring them before and after feeding with calipers. In those instances setback occurred but was not detected.
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Old May 22, 2020, 06:57 AM   #11
zeke
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Am of belief most people back in the day just didn't check for it. The first real 45 acp plus p defensive rounds i bought were the Rem 185 plus p's. Up here they were the only commonly available versions. Setback was horrendous, and easily visible. Never saw any magazine article ever mention it. In my experience Federal was among the first to produce defensive rounds with min to no setback. Either way, it is possible to hand load rounds with no setback, which i do when loading high velocity jhp's.

Kinda like bullet pull. The only time you here it mentioned is in regards to revolvers.
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Old May 22, 2020, 01:17 PM   #12
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Quote:
The 1911 is a big offender with respect to setback.
I think it is an error to blame the gun. The problem, when it occurs, is with the ammo.
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Old May 22, 2020, 02:58 PM   #13
74A95
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Quote:
Originally Posted by 44 AMP View Post
I think it is an error to blame the gun. The problem, when it occurs, is with the ammo.
But that's what you did when you wrote:

Quote:
I suppose "modern" guns are designed to produce setback . . .
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Old May 22, 2020, 05:54 PM   #14
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I thought I was proposing a theory. of course if you're not willing to quote the entire sentence it will seem different...

so, I'll restate it,

Are the more modern designs (say from the 80s up) more likely to set back current ammunition? Do striker fired polymer frame designs do it more often than 1911 variants? I don't know....what do you think?

Does it happen with .45s due to the use of 8rnd mags, rather than the original 7 rounders?

Again, I don't know. What I do know is that I've seen some ammo chambered and rechambers A LOT, where setback did not happen, so I believe it is something that is not inevitable, does not have to happen, and rounds where is does happen are simply not made as well as rounds where it does not happen.

What I don't accept is the answer that "oh well, that's just something that happens," because I've seen where it doesn't.
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Old May 22, 2020, 06:27 PM   #15
74A95
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Quote:
Originally Posted by 44 AMP View Post

Are the more modern designs (say from the 80s up) more likely to set back current ammunition? Do striker fired polymer frame designs do it more often than 1911 variants? I don't know....what do you think?

Does it happen with .45s due to the use of 8rnd mags, rather than the original 7 rounders?
The angle at which the rounds feed and how that affects the surfaces they contact would produce different amounts of 'impact force' and the greater the impact force the more likely setback would occur.

Setback occurs in 7 round 1911 mags, too. The first round from an 8 round mag will nosedive a little more than the first round from an 7 round mag, so it would be striking the feed ramp at a slightly steeper angle and has the potential for producing more setback. As more rounds are fired and the number of rounds in the magazine declines, they feed at higher angles and nosedive less, which should reduce setback.

Single stack magazines in which the rounds sit at an angle are especially prone to nosedive because of how the rounds fit in the magazine. It's an inherent design feature and it does not matter if they are old designs or new designs.

Double stack magazines, more common on newer gun designs, if designed correctly, can reduce nose dive which reduces one source of angular impacts. But the bullet still hits stuff as it feeds into the chamber, and this can produce setback.
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Old May 23, 2020, 12:15 AM   #16
seanc
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Thanks guys! I appreciate EVERYONES responses: some history, some good observations based on all your experience. I don't measure every round, just sometimes if a round catches my eye.

For practice loads, I'm not really worried about setback since 99.99% of the time, it's a 1 shot proposition (pun intended). I was just leary about how tight a crimp I was getting from the seater/crimper die and was pleasantly surprised at how good it held vs. a dedicated crimping die and since Clays can get spikey, especially when compressed. My loads were pretty soft, next time I'm going to try Titegroup and see how 5.6gn feels vs. the Clays. I'll eventually finish off my supply of Clays and just stick with Titegroup for everything: 9, 380, 45.
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Old May 23, 2020, 01:49 AM   #17
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Back in the early 70s when I started reloading, one of the bits of advice was that when setting your seating & crimping die to see if you had enough crimp was to put the bullet nose against the bench, and push (hard) to see if the bullet moved any.

I haven't bothered doing this for a long time, but it occurs to me that it might be a test you could perform with factory ammo as well as your handloads, particularly defense ammo. I would not expect any setback, but if you got some, it might be something worth knowing.
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