fact or myth?

[Walt Sherrill]

But after 50 repeated runs, I fired the round. It fired. Don't know what else to say.

Can't say that necessarily establishes anything, but in at least that case, 50 chambering of the round didn't appear to cause any problems.

The round will almost certainly fire -- that's not the issue. That you had a round go off wasn't surprising. But you obviously didn't understand that what you were doing was potentially very dangerous.

With round setback, the pressures generated inside the round can increase, sometimes substantially, and that increased pressure can lead to a damaging explosion that could have damaged both the gun and YOU!!

It would have made far more sense to simply measured the round after it had been chambered so many times, but since you didn't understand what the consequences of bullet setback could do, you weren't concerned.

If setback is an issue, it can be measured by using a micrometer (or in some cases, a ruler.) Setback rounds need to disposed of safely or disassembled and reloaded.

 

[Rinspeed]

Here's some "science" for you. Because I'm data-driven (and a big nerd) I once went to the range to test this. I ejected and reloaded (from magazine) the same hollow point round 50 times. I did get a few funny looks and one "do you need someone to show you how to shoot?" offer

But after 50 repeated runs, I fired the round. It fired. Don't know what else to say.

Can't say that necessarily establishes anything, but in at least that case, 50 chambering of the round didn't appear to cause any problems.

I wouldn't try that with a .40 S&W, it only takes 1/10th of an inch of bullet setback to double the chamber pressure.

 

[JohnKSa]

But after 50 repeated runs, I fired the round. It fired. Don't know what else to say.

As others have pointed out, the issue isn't that setback renders the round inert, it is that it can result in the discharge pressure skyrocketing. Fortunately, in your case, either the round didn't set back much, it wasn't a loading that was especially sensitive to setback, it was a round that was very mild to begin with, the ammo manufacturer had taken precautions to minimize or eliminate setback (e.g. case cannelure), or some combination of the above.

I wouldn't try that with a .40 S&W, it only takes 1/10th of an inch of bullet setback to double the chamber pressure.

The data I have seen suggests that some 180gr loadings in .40 S&W can double in discharge pressure from a tenth of an inch of setback. I haven't seen data indicating that all .40S&W loadings, or even all 180gr .40 S&W loadings are that sensitive.

...in a visual comparison in terms of bullet exposed even after a number of times with both Speer Gold Dots and Federal HST there is little difference...

I remember reading information from one particular ammo maker that claimed their self-defense ammo would not setback at all from 4 chamberings but that they wouldn't guarantee it past that. Unfortunately I can't find that cite any longer and I don't remember which company made the claim.

Anyway, based on that information, IMO, premium self-defense ammo shouldn't set back at all from being chambered a few times. If it does, the ammo maker in question should be contacted.

 

[Nanuk]

A pistol is not a car or truck. Being a mechanic does not make one an armorer or a gunsmith.

The primers can actually disassemble themselves from repeated chamberings. It has happened to cops who loaded/unloaded the same round over and over over a period of time.

 

[44 AMP]

All brands and quality levels of ammunition can suffer bullet setback.

It certainly seems to be the case, these days. However, "can" does not mean "will" or "should".

Chambered 50 time?? piffle!

I knew a fellow who bought some Federal 185gr JHP .45ACP in 1980. He kept the last magazine full as his home defense ammo. Between 1980 and 2002 when he finally shot them off, those rounds were chambered and rechambered HUNDREDS, if not thousands of times. The nickeled cases had brass stripes on them. All the nickel was worn off the edge of the rim. The bullets NEVER set back on any of those rounds. And, yes, they were measured quite often, to see if it happened. It never did. The gun was a Sig P220.

And when fired that ammo performed exactly the same as it had done over 20 years earlier when new. Function was flawless and accuracy was perfect point of aim at 25yds.

I mention this, not to imply in any way that today's ammo will do this, or should be expected to do this, but to show that bullet setback is not something that HAS to happen, rather something that usually does happen, these days. And, I say "these days" because, to the best of my recollection, while it has always been a possibility, it wasn't enough of an issue back in the 60s & 70s that much was written about it, then.

Clearly something has changed over the years, probably quite a few things.

 

[Walt Sherrill]

I mention this, not to imply in any way that today's ammo will do this, or should be expected to do this, but to show that bullet setback is not something that HAS to happen, rather something that usually does happen, these days. And, I say "these days" because, to the best of my recollection, while it has always been a possibility, it wasn't enough of an issue back in the 60s & 70s that much was written about it, then.

Clearly something has changed over the years, probably quite a few things.

Not the least of them being the internet and the existence and wide participation in forums like this.

It may be that ammo is just as well made as ever, but we now have a place to rant, warn, or say what we believe. In the '60 and '70s darned few gun magazines paid that much attention to semi-auto handguns (they had NOT really caught hold back then) -- and there wasn't many other places to share experiences.

 

[44 AMP]

Might be the ammo is as well made as it always way, might not be, I can't say, but logic does suggest that if the public is willing to accept ammo that is good enough to stand a few chamberings, then making ammo that will stand unlimited chambering is a waste of money.

Maybe the newer semi auto designs, so popular in large numbers slams the rounds harder than the older designs, perhaps with the intent of increased reliability. We know Glock deliberately uses chambers that aren't fully supported, for increased feed reliability.

There's nothing morally wrong with that, nothing says guns intended for military use have to be reloader friendly. Few are, these days. And, ammo that sets back (or has the bullet pulled by recoil) needs to be replaced, which means you buy more ammo, sooner. Good for the ammo companies, I'm sure.

If I missed reading a single issue of Guns & Ammo, Shooting Times, and the American Rifleman from the 60s through the 90s, its a very small number. And, I have nearly complete collection of American Rifleman from 1948 through the 90s when I decided to stop accumulating them, because I couldn't afford a bigger house.

I think there were a lot of articles about semi auto pistols, its just that in before the wondernine explosion there weren't a dozen makers producing 30 different variants of 3 basic designs, each...

Bullet setback? Reloading manual, and articles would all tell you about pushing the nose of the loaded round against the bench (firmly), or something similar, to check for setback, as part of the QC for your handloads. Don't recall much else ever being said about it, even in the Q&A columns. Maybe it existed as a problem back then, but if it did, why not talk about it, we talked about a lot of problems back then, though not nearly like we can today.

And that is probably part of it, as well, with our internet instant communication, and nearly unlimited space, it is quite different from a monthly, printed magazine.