Rounds no good after chambering?

[smokeyandthebandit05]

New Jersey State Police | February 23, 2007 | New Jersey State Police-


Catastrophic Failure of Semiautomatic Handguns


The following bulletin was received from the New Jersey State Police - Officer Safety Division


Date: February 23, 2007



Continuous reloading and chambering of the same round may cause catastrophic failure in semiautomatic handguns.


The Security Force at the Los Alamos National Laboratory in Los Alamos, New Mexico, recently reported on the catastrophic failure of a semiautomatic handgun when it was fired. The internal explosion caused the frame to break while the slide and barrel separated from the weapon and traveled down range. No one was injured in the incident. An investigation revealed that security personnel were repeatedly charging the same round of ammunition into the chamber.


Technical personnel at Glock Inc. advise that repeated chambering of the same round may cause the bullet to move deeper into the casing, further compacting the propellant. When a normal cartridge is fired, the firing pin hits the primer, igniting the propellant. When the propellant burns, the gas pressure drives the bullet out of the case and down the barrel. However, if the propellant has been compacted, the pressure may increase beyond the gun's specifications, causing the weapon to break apart.


Sigarms Inc's personnel confirm that reloading the same round five or six times will cause the problems, noting that reloading the same round even once will void their warranty. Both manufacturers stress that the problem is not with the gun, but with chambering the same round repeatedly.


The NJ Regional Operations Intelligence Center urges all law enforcement officers not to chamber the same round when loading their weapons.


**For example, when you clean your weapon, most of us drop the magazine and then pull the slide back thereby ejecting the round in the barrel. After cleaning the weapon many of us will return the "same" round to the barrel that we initially extracted. Each time the slide slams forward on that same round it seats it deeper into the cartridge. Apparently, by seating the round deeper into the cartridge, it creates greater pressure when the round is intentionally detonated by a firing pin strike causing the weapon to explode. **


I just dont get it lol

 

[Jeff82]

What's not to get?

 

[FC]

Easy, don't buy a Glock if you don't want your gun to explode I'm surprised more don't just drop a round in the pipe when they close the action and put in a full magazine.

 

[altitude_19]

There are stories that damages the extractor.

 

[doc2rn]

I can personnaly attest to this I had a G32 Kaboom on me. Factory claimed it was me firing a round that had been chambered before. Funny thing is I was in the middle of the box at the range when it happened.

 

[Shadow 7D]

Its a know phenomenon, and depends on the caliber, some rounds and loads are likely to be set-back

Basically, the bullet is pushed back into the cartridge, causing the volume to decrease, leading to a higher initial pressure when the round is fired, that's the reason, when reloading, that the unfilled (empty) part of the case is also important, like someone has done alot of research on this.

 

[txhoghunter]

When I chamber a round in my AR (I know not a pistol, but the same concept applies), the primer gets a small hit. Not enough to discharge the round, but if I kept chambering, unloading and re-chambering the same round I could see it discharging.

Maybe not what happened, but I could see it.

 

[Manco]

Avoiding bullet setback is precisely why I only ever chamber any cartridge once. Any personal defense cartridges that have been manually extracted are set aside for practice at the range. Well, I guess that means they're going to be chambered one more time, but that should be alright, especially because the ones I use have a tight fit between the bullet and case, and are sealed tight with asphaltum. Nope, I don't like taking any chances with exploding guns --especially when it's avoidable.

 

[Sam1911]

I just dont get it lol

Yup. Not sure what there is not to "get." Bullet setback certainly does happen, and it is easily measurable. I've experienced it myself with carry ammo.

As the round is pushed forward by the closing slide, the bullet hits the feed ramp. Make the same bullet hit the feed ramp 20, 30, 50, 100+ times, and it will eventually loosen up and set back into the case a bit. I think almost everyone knows and understands the dangers of a compressed load.

Pounding a bullet back into a case certainly can cause pressures to spike dramatically when that round is fired.

just drop a round in the pipe when they close the action and put in a full magazine

This is not considered to be a very good practice with most handguns as the extractor is designed to allow a cartridge to slide up from beneath, rather than having to snap over the rim. Many guns handle it well enough, but is it harder on the gun than it needs to be.

The usual procedure is to insert a full mag, chamber a round and apply any safeties, drop the mag and top it off with one more round, reinsert mag, and holster.

 

[Mainsail]

Set-back has nothing to do with the gun, and ANY handgun can have a catastrophic failure from repeatedly chambering the same round. If it makes you feel superior in some way to talk trash about Glocks, have a good time but you’re only diminishing your reputation. I owned a Glock 17 from 1987 until about 2003, and I never even heard of problems with any Glock pistol until the .40 S&W came along. I have no worries about my G20 or G29 in 10mm.

I don’t know why anyone would need to keep unloading their handgun; it’s easy enough to put it in the safe loaded. If I unload any of my loaded handguns, I try to rotate the round to the bottom of the magazine.

 

[NoAlibi]

From the OP: "Sigarms Inc's personnel confirm that reloading the same round five or six times will cause the problems..."

After several decades of reloading and shooting I'm sure I've re-chambered a round several times. Less so in my reloads because I burn 'em up at a high rate, but my SD ammo gets more handling than shooting. To date, I've not seen or heard a hint of an over pressure round.

That doesn't mean I just haven't been lucky so far. I am not going to discard a round that has been previously chambered, but from now on I will set it aside and measure the COAL before I use it again.

Thanks for the tip.....Doc

 

[Sam1911]

I am not going to discard a round that has been previously chambered, but from now on I will set it aside and measure the COAL before I use it again.

For my part, I can visually tell whether a bullet has set back -- with at least enough accuracy to make me feel comfortable. But I usually carry a .45 so the pressures are low enough to forgive very small OAL changes.

When I've had bullets set back, it was pretty noticeable but YMMV, as they say.

 

[CAS700850]

I was taught to avoid re-chambering the same round too many times because the process of being chambered and ejected can cause damage to the case rim, which in turn can lead to malfunctions. Set-back seems like a more serious concern to me.

 

[shotgunjoel]

When I chamber a round in my AR (I know not a pistol, but the same concept applies), the primer gets a small hit. Not enough to discharge the round, but if I kept chambering, unloading and re-chambering the same round I could see it discharging.

That's because the AR had a floating firing pin. It holds inertia when the bolt slams shut. Since there is not spring stipping it, its small inertia is enough to put that little dent in the primer. As far as I know, most psitols don't have floating firing pins.

 

[Jim K]

I don't claim that my tests were either exhaustive or definitive, but I once tried this with several brands of 9mm factory loads, forcing the bullet further in to the case in 1/10" increments until either the bullet was crushing the powder or the thicker part of the case would not allow the bullet to seat further without swelling the case to the point it would not chamber.

I fired dozens of rounds of each of 5 brands, with bullet seating as described. I not only did not blow up the gun, I didn't even get any signs of excessive pressure. The bullets seated so they crushed the powder gave slightly flattened primers.

Further, I found that the bullets were all hard to push down into the case. I did not find any of the brands in which repeated chambering (up to 100 times) moved the bullet at all. I finally used a vise to press the bullets deeper into the cases.

Can repeated chambering of a cartridge actually drive the bullet deeper? My tests say no, but it could be possible. Can firing cartridges with the bullet seated deeper than factory result in pressure high enough to blow up a gun? Again, my tests say no.

Again, note that I obviously did not try every gun and every make of ammo, nor did I fire thousands of rounds. But my tests convince me that the story is either completely false or there is some other cause for the blowups.

Jim

 

[Manco]

That doesn't mean I just haven't been lucky so far. I am not going to discard a round that has been previously chambered,

Well, I shoot these rounds at the range. Granted, they're more expensive than my normal range ammo, but that's OK because I only dispose of very few such rounds. I suppose that those who unload their guns frequently for some reason would be less inclined to do the same, but except for occasional dry-fire practice at home, I don't mess around with my guns a lot outside of the range, so it works for me.

but from now on I will set it aside and measure the COAL before I use it again.

The problem is that the bullet could be set back the NEXT time you chamber the round, even if it measures within normal range right beforehand. If you could measure it while it's inside the chamber, that would be different.

Now, I don't mean to be an alarmist, as I think you'd have to chamber a round quite a few times to incur a substantial risk, with several chamberings being acceptable, in my opinion, but personally I've decided to play it safe and allow only a single chambering (or actually two when I shoot the round). It makes me feel all warm and fuzzy, and I don't mind a little bit of practice with personal defense ammo anyway.

Those who frequently unload their defensive weapons and therefore do not wish to discard already-chambered rounds should, in my opinion, either refrain from doing so (yeah, I know-- ) or ride the slide down nice and gentle when reloading, which should take a lot of pressure off the bullet. The latter may not work well with some guns (the cartridge could get hung up in the chamber, for one thing), but most should tolerate it just fine (mine do). Make sure that the extractor engages the rim properly and that the gun goes fully into battery, of course.

But I usually carry a .45 so the pressures are low enough to forgive very small OAL changes.

Generally the higher the pressure and the shorter the cartridge, the greater the risk involved. Those who shoot .40 S&W, for example, should take bullet setback very seriously, in my opinion. And those who shoot .357 SIG should take it even more seriously since the bullets are easier to set back. Sure, you could do nothing, and nothing may ever happen anyway, but the risk is still very real (albeit small, in the grand scheme of things) and can be virtually eliminated if you care to take appropriate steps. If not, then good luck and I hope that your gun doesn't explode.

 

[Shadow 7D]

.40 is the round MOST associated with the 'blowups'

And there are MANY factors, esp as what the bullet weight, what the powder was, what the load was.

 

[aryfrosty]

Easy, now...

Come on guys...It isn't just Glocks that experience this phenomena. That original post included info from Sig as well. My habit has always been to rotate the ammo in my mags at least everyother shift. I didn't mike the rounds but I believe that my eye would have caught a radical shortening. Old habits die hard, but I also waste a lot of ammo by firing it all up once a month. When you carry as a means to stay alive and kicking you can't afford to take for granted that your ammo is dependable. I want that stuff to go bang if I need for it to.

 

[dfariswheel]

Another danger of bullet set-back is a failure to feed the second round.

This turned up early in the police switch to the automatic pistol.
After repeated chamberings pushed the bullet back, the shorter over all length cause "second round stoppages".
The gun would fire the first round, but fail to feed the second.

A good trick is to get a factory-new round and use it as a gage to inspect used rounds for set back.
Simply compare them to the new factory "control round".

Bottom line is, if you don't want over pressure rounds causing a KA-BOOM or a second round stoppage, don't chamber the same round too many times.
Most police-grade ammo is built to last for 4 to 5 chamberings before being shot in practice or discarded.

 

[Jim Watson]

I don't unload and reload my house and carry guns daily, so risk of bullet setback is small.
Eventually they will get run through several times, though. If I see any setback or just a collection of rub marks, the round is demoted to practice.

The only time I have ever had anything that MIGHT have been caused by setback was the time I loaded some plated SWCs in lieu of cast SWCs to reduce smoke shooting indoors.
I got a lot of failures to extract. I think those soft slick plated bullets were setting back and raising pressure enough to swell the brass in the chamber. Maybe. I know I applied every adjustment I could think of or read about and nothing made much difference.
I now have a tool to cannelure the brass at the base of the bullet like some factory loads, which I use on 185 gr JHPs with their short bearing surface and shallow seat.

 

[RedAlert]

Interesting. If you follow the guidance given to NOT re-chamber a round, what are you supposed to do with it? Toss it? Break it down and reload? I'd suggest you should measure the OAL and then if too short, break it down or toss it.

 

[Thlax]

Along with RDF what are you supposed to do... Say I'm carrying SD ammo, go to the range, eject my 1 SD bullet and mag then put in Blazer. Does that loaded SD round become trash? Should I just shoot it at the range that trip?

 

[NoAlibi]

Manco: "The problem is that the bullet could be set back the NEXT time you chamber the round, even if it measures within normal range right beforehand."

Let me see if I got this right. I take my set-a-sides measure the COAL, find that they are within tolerance and the next re-chambering will drive the bullet so deep that it will blow up?

Using your logic what makes you think that there isn't any possibility that a never chambered round won’t set the bullet back on the initial chambering "unless you can measure it while it is in the chamber" (Your words)? Please...

In the realm of "anything is possible" it might behoove you, for the sake of safety, never to use an auto-loader.

 

[The Wiry Irishman]

Further, I found that the bullets were all hard to push down into the case. I did not find any of the brands in which repeated chambering (up to 100 times) moved the bullet at all

I've noticed its very brand dependent, and bullet type dependent as well. I used to carry Gold Dots (.45 ACP), and they'd seat themselves deeper pretty quickly. The HSTs I carry now don't seem to move at all. I've never had any issue with FMJ of any kind, though. I suspect its because the flat tip of a HP digs into the feed ramp more, but that's just speculation on my part.

 

[jbkebert]

I have honestly never heard of this. Perhaps I should change my practices. When I get home I clear my gun and place the round back in the top of the mag. In the morning I rechamber and go on about my day. My possibly only saving grace is that I ride the slide back up. Checking sure that the slide goes fully into battery drop the decocker and go.

I hate it when people constantly just drop thier slide day after day. Puts to much wear on the gun for no reason IMHO.