[tango44]

Bullet setback caused by chambering a round several many times.
Just don't shoot it, it can elevate pressure to dangerous levels!

 

[Allen Bundy]

I think that y'all trying to trigger my OCD. Now I'll be at the range measuring my rounds with a caliper before loading them into the magazines!

But seriously, thanks for the heads up. I will be measuring any round that was previously chambered before using it again.

 

[jkallner]

Never happened to me.

Me neither cremaley, I'm interested in the circumstances behind how it happened to the OP. I saw some Remington 357 Sig ammo a couple of years ago that had the bullet pushed in, but I can kind of get it with that ammo, not so much for Hornady Critical Defense.

 

[ClayD]

I think that y'all trying to trigger my OCD. Now I'll be at the range measuring my rounds with a caliper before loading them into the magazines!

But seriously, thanks for the heads up. I will be measuring any round that was previously chambered before using it again.

You should also weigh each round to detect under or over powder charges...

 

[Allen Bundy]

You should also weigh each round to detect under or over powder charges...

I should probably just load my own rounds. I had a friend that did his own loading primarily because he wanted more uniform cartridges.

 

[PilatusTurbo]

LoL minor setback isn't a big deal. Ask me how I know... Now if half the projectile is jammed back into the casing, either get a puller or discard that round. Seriously, a little setback is no big deal. If it's standard pressure ammunition, not +P or whatever, it's fine. The guns are rated for +P, so don't stress. You can google image search how much setback becomes an issue.

 

[steveac7531]

That’s definitely an ammo issue.

 

[jkallner]

I think that y'all trying to trigger my OCD. Now I'll be at the range measuring my rounds with a caliper before loading them into the magazines!

But seriously, thanks for the heads up. I will be measuring any round that was previously chambered before using it again.

You can measure them, but suppose your calipers are off? I suggest double checking with 2 sets of calipers and of course, if they disagree, you need a third caliper to establish which one of the is right. Digital calipers only of course!

 

[jpg19]

As others have mentioned, you left off some data needed to discuss your issue. What Sig Model? Is it a new from the factory pistol or a used firearm new to you? Have you tried other ammunition in your Sig? What brand of ammunition and is it factory new ammunition or reloads? Have you used the same ammunition with your other pistols?

There appears to be scratches and wear on both rounds. Were there any issues with chambering the rounds other than the setback on the one round?

It’s a brand new Sig P365 and this ammo has been rechambered many, many times. I unload the firearm every night and leave a full magazine in the pistol but nothing in the chamber as we have 3 kids. We are saving to buy a safe since they’re finally getting older. The ammo is Hornady Critical Defense. This has happened to 4 of these rounds since I purchased them, however it has never happened with my Glocks or HK so its curious to me that as soon as I get my Sig, this starts happening. I didn’t realize you shouldn’t rechamber a round more than twice, thanks for the advice guys. I’m curious what you all think about the fact that neither of my Glocks (19 and 43) nor my HK (VP9SK) have had this happen with me doing this for over 10 years?

 

[PilatusTurbo]

I'm totally in your same boat. I just bought a Locking cabinet a couple years back, and a locking ammo cabinet last summer. My boys are now 4 and 5, so it was time to do more than leave them on the top closet shelf, or just de-chambering them, as I used to do, also.

Yes, I can assure, most handguns will cause set back if the rounds are repeatedly chambered; you probably just never did pay as close attention to it until now. The action, ramming the round into the feed ramp, and up and into the breech is not a pleasant event. It can cause setback after just one or two times. Quality ammo with a good crimp, it shouldn't really happen. Just did it with my Sig V Crown, and it didn't set back two rounds I test chambered on my new project.... However, I had some pandemic production era Ammo Inc JHPs and a round nosedove into the feed ramp on another gun. It literally pressed the projectile 2/3 of the way back into the case. Glad I tap rack banged that one outta the way, and picked it up to examine and discard it. Good crimping is good.

 

[jkallner]

I’m curious what you all think about neither of my Glocks (19 and 43) and HK (VP9SK) not doing this for over 10 years?

I don't know about the HK, but it doesn't surprise me that you didn't experience this with the Glocks - their chambers are, let's say, generous, so the bullet doesn't come in contact with it as much as the Sig. Sort of putting a baseball through a basketball hoop kind of thing. Not Glock bashing, that generous chamber is one reason why they are so reliable.

 

[Redneckbmxer24]

Yeah, for real.

If I have to de-chamber the gun for whatever reason, I came up with a way to re-chamber the round without it having to hit the feed ramp. I'm sure I'm not the only one who does something like this. It's not straight breech loading, but it is with a twist.

Lock slide back, breech load the round. Holding slide, release slide stop, slowly allowing the slide to contact the round in the pipe. This way the extractor won't slam into the rim of the cartridge. Then, I place my fingers on the left side of the gun, cradling it with the extractor side up. I then use my thumbnails to press the rear of the extractor and it pops right over the rim. Been doing it this way for a long time, and it's just fine. Doesn't hurt anything.

Reduces setback for events like cleaning, or whatever may require you to make the weapon safe, etc.

This 100%, been doing this for years. Doesn’t work on all guns thought depending on extractor design but does work on P365’s.

 

[Redneckbmxer24]

It’s a brand new Sig P365 and this ammo has been rechambered many, many times. I unload the firearm every night and leave a full magazine in the pistol but nothing in the chamber as we have 3 kids. We are saving to buy a safe since they’re finally getting older. The ammo is Hornady Critical Defense. This has happened the 4 of these rounds since I purchased these rounds, however it has never happened with my Glocks or HK so its curious to me that as soon as I get my Sig, this starts happening. I didn’t realize you shouldn’t rechambered more than twice, thanks for the advice guys.I’m curious what you all think about neither of my Glocks (19 and 43) and HK (VP9SK) not doing this for over 10 years?

I figured rechambering the same round was the culprit here. It’s got nothing to do with the gun, I assure you that others will do it too, in fact I learned this lesson the first and second time myself on a G19. There’s never been a third time for me because I figured it out.

You simply can’t just keep rechambering the same round, the crimp will give out and bullet will set back. Repeated rechambering will also deform the bullet and can cause accuracy issues and effect bullet terminal performance. If you must unchamber a round then rechamber using the method Pilatusturbo posted. Don’t just let the slide go home though or then you’ll be replacing your extractor or will damage the rim of the case and may not extract when you need it to.

 

[PilatusTurbo]

Yeah, it won't work on guns with shorter extractors like Glocks, etc. Glad I wasn't the only one doing this

 

[jpg19]

I don't know about the HK, but it doesn't surprise me that you didn't experience this with the Glocks - their chambers are, let's say, generous, so the bullet doesn't come in contact with it as much as the Sig. Sort of putting a baseball through a basketball hoop kind of thing. Not Glock bashing, that generous chamber is one reason why they are so reliable.

That makes perfect sense, thank you for sharing your input.

 

[Redneckbmxer24]

The pressure on the bullet causing it to uncrimp and push back in the case happened at the feed ramp, not the chamber. Glock chamber being large has nothing to do with anything, rechamber the same round over and over in a Glock and eventually it’ll do it too.

 

[jpg19]

Yeah, it won't work on guns with shorter extractors like Glocks, etc. Glad I wasn't the only one doing this

Apparently something went right over my head throughout this post, although I admit I am simultaneously busy with more important things at the time. What won’t work on guns with shorter extractors?

 

[PilatusTurbo]

Apparently something went right over my head throughout this post, although I admit I am simultaneously busy with more important things at the time. What won’t work on guns with shorter extractors?

I'm sorry, I meant looking at the extractor from the right side of the slide. If the extractor is longer, it can work. Glocks and others have shorter extractors. Lemme add this pic: Top slide has what I refer to as a 'shorter extractor' and our trick of rechambering won't really work on it. Bottom slide, has the 'long extractor' and our trick will work on extractors like that. Our Trick from my previous post: Lock slide back, breech load the round. Holding slide, release slide stop, slowly allowing the slide to contact the round in the pipe. This way the extractor won't slam into the rim of the cartridge. Then, I place my fingers on the left side of the gun, cradling it with the extractor side up. I then use my thumbnails to press the rear of the extractor and it pops right over the rim. Been doing it this way for a long time, and it's just fine. Doesn't hurt anything.

 

[Allen Bundy]

PilatusTurbo,

Thanks for the chambering tip. I'll give that a try. I would imagine that would reduce the likelihood of bullet setback loading the chamber by hand.

 

[PilatusTurbo]

The pressure on the bullet causing it to uncrimp and push back in the case happened at the feed ramp, not the chamber. Glock chamber being large has nothing to do with anything, rechamber the same round over and over in a Glock and eventually it’ll do it too.

Thank you. It has to do with the nose of the round ramming into the bottom of the feed ramp. If you slowly cycle a gun, holding everything tight and slowly allowing it to work, you can observe this. Even an AR-15 operates by the same principles. Also, it probably won't cycle or load the round properly when doing this in hand holding slow motion, as it's a quick, violent action that is timed and designed to work under certain speeds, force amounts, spring tensions, etc. The round getting jammed into, and up the feed ramp is not a nice process, but it works very quickly, so we many times never really see what happens, as it happens.

The way headspacing works, the chamber itself won't ever really cause set back. Even if the 9mm round was slightly out of spec on the larger side, which I have seen, it's probably less likely to loosen at the crimp and set back. It probably won't go into battery, or eject very nicely, either.