quote:

Originally posted by egregore:
You don't necessarily have to rechamber the very same round. Your magazine is out of the gun but still filled, I assume. Insert the mag, chamber the top round, remove the mag, load your loose round into the mag, and insert the now fully-loaded magazine. That reduces the wear and tear on any one cartridge.

Yes, of course, but as one gentleman points out up above, every time you shoot that pistol you just alternate between the top two rounds unless you purposefully dump the mag and put the one that was chambered down on the bottom each time. So if you shoot every week and use your defensive ammo for a year before replacing, the top two rounds would still have 25-ish rechamberings on them.

quote:

Originally posted by TheMan:

quote:

Originally posted by egregore:
You don't necessarily have to rechamber the very same round. Your magazine is out of the gun but still filled, I assume. Insert the mag, chamber the top round, remove the mag, load your loose round into the mag, and insert the now fully-loaded magazine. That reduces the wear and tear on any one cartridge.

Yes, of course, but as one gentleman points out up above, every time you shoot that pistol you just alternate between the top two rounds unless you purposefully dump the mag and put the one that was chambered down on the bottom each time. So if you shoot every week and use your defensive ammo for a year before replacing, the top two rounds would still have 25-ish rechamberings on them.

That's a fact.

When I was policing, we carried the 357SIG, and we saw setback in Speer gold dots. It was always from the guys who went home and emptied their guns (for whatever reason).

It came to light after about a year after our switch from 9mm. One of the firearms instructors found several guys with setback. So inspecting the ammo was added to our quarterly weapons inspections. The Sgt would announce an inspection at roll call, everyone would download their mags and pistol. And you would line up all your rounds, the Sgt would place a ruler across the top of the projectiles and he took any short ones. He gave you replacement rounds and we went about our day.

No one blew up a pistol. The firearms instructor was just being cautious. I used to reload 356SIG and intentionally setback a few rounds and tried them. I didn’t blow up a gun. The bearing area to crimp a round is very short on the 357 SIG, and the case has a short neck. We even shot the short rounds that he confiscated and we didn’t have issues.

But I think it’s a good idea not to fire short rounds.

I only unload my EDC when I go into my kid’s school or someplace I can’t carry. I download the gun, and handcuff it to the frame of my trucks seat. So in the last year I’ve maybe rechambered that round six or seven times. If the round begins to show setback, I’ll replace it. I shoot my carry ammo one a year. Mostly the rim gets chewed up by the extractor.

You guys had me worried since I carry 357 sig all the time... So I emptied the 3 magazines I always have loaded including the one in the pistol and did a visual check and they all looked good. Did not do the ruler thing, maybe next time.

Good and useful post.
Thank you.

I remember some years ago seeing a photo of a bunch of 40 S&W cartridges with obviously set back bullets right out of a new factory box. In thinking of the people we see shooting at public ranges or handling guns in a store, how many would think to check their ammunition then or worry about what was happening when they rechambered rounds over and over? My contention is that if the setback issue was as dangerous as some believe, guns would be blowing up right and left all the time, and yet how many of us here have ever seen or even heard of its happening?

What I have seen, though, is damage to the hollow point bullets in defensive ammunition. When I started inspecting ammunition along with my agency’s guns, I once found a Winchester hollow point bullet that was so deformed that the lead core had separated from the jacket at the nose. I believe that guy must have been chambering the same round every day and followed the advice to let the slide slam forward at full speed every time to damage the bullet like that.

I have training guns and therefore chamber my carry cartridges very infrequently, but when I do, there’s no reason to let the bullets hit the feed ramp at full speed. I control the slide so it goes forward slowly when chambering carry ammo. We shouldn’t do it in training so as to avoid bad habits in a critical situation, but there’s no reason why we cannot do that with our carry ammo. I usually carry 357 SIG Gold Dots and when I do inspect the ammunition, I’ve never seen any setback or damage to the bullets which have large hollow points and with thin edges as compared with my favorite 9mm loads.

quote:

Originally posted by MikeinNC:

I used to reload 356SIG and intentionally setback a few rounds and tried them. I didn’t blow up a gun. The bearing area to crimp a round is very short on the 357 SIG, and the case has a short neck. We even shot the short rounds that he confiscated and we didn’t have issues.

Here's a test of setback CCI/Speer did years ago. Never even came close to a dangerous pressure level.

quote:

Originally posted by TheMan:

quote:

Originally posted by egregore:
You don't necessarily have to rechamber the very same round. Your magazine is out of the gun but still filled, I assume. Insert the mag, chamber the top round, remove the mag, load your loose round into the mag, and insert the now fully-loaded magazine. That reduces the wear and tear on any one cartridge.

Yes, of course, but as one gentleman points out up above, every time you shoot that pistol you just alternate between the top two rounds unless you purposefully dump the mag and put the one that was chambered down on the bottom each time.

Which is what I've been doing. But, from what I'm reading here, that has been excessive caution.

quote:

Originally posted by Flash-LB:
Here's a test of setback CCI/Speer did years ago.

Excellent information. Thank you.

There are also concerns with the primer failing with repeated rechamberings of the same round.

THE FOLLOWING TRAINING ADVISORY WAS FORWARDED FROM GWINETT COUNTY
POLICE DEPARTMENT – LAWRENCEVILLE, GA

In September of this year a GCPD officer was involved in a situation which quickly became a use of deadly force incident. When the officer made the decision to use deadly force, the chambered round in his duty pistol did not fire. Fortunately, the officer used good tactics, remembered his training and cleared the malfunction, successfully ending the encounter.

The misfired round, which had a full firing pin strike, was collected and was later sent to the manufacturer for analysis. Their analysis showed the following: “…the cause of the misfire was determined to be from the primer mix being knocked out of the primer when the round was cycled through the firearm multiple times”. We also sent an additional 2,000 rounds of the Winchester 9mm duty ammunition to the
manufacturer. All 2,000 rounds were successfully fired.

In discussions with the officer, we discovered that since he has small children at home, he unloads his duty weapon daily. His routine is to eject the chambered round to store the weapon. Prior to returning to duty he chambers the top round in his primary magazine, then takes the previously ejected round and puts in back in the magazine. Those two
rounds were repeatedly cycled and had been since duty ammunition was issued in February or March of 2011, resulting in as many as 100 chambering and extracting cycles. This caused an internal failure of the primer, not discernible by external inspection.

This advisory is to inform all sworn personnel that repeated cycling of duty rounds is to be avoided. As a reminder, when loading the weapon, load from the magazine and do not drop the round directly into the chamber. If an officer’s only method of safe home storage is to unload the weapon, the Firearms Training Unit suggests that you unload an entire magazine and rotate those rounds. In addition, you should also rotate through all 3 duty magazines, so that all 52 duty rounds
are cycled, not just a few rounds. A more practical method of home storage is probably to use a trigger lock or a locked storage box.

FURTHER GUIDANCE:

The primer compound separation is a risk of repeatedly chambering the same round. The more common issue is bullet setback, which increases the chamber pressures often resulting in more negative effects.

RECOMMENDATION:

In addition to following the guidance provided above of constantly rotating duty ammunition that is removed during the unloading/reloading of the weapon, training ammunition utilized during firearm sustainment and weapon manipulation drills, should also be discarded if it has been inserted into the chamber more than twice. This practice lessens the
likelihood of a failure to fire or more catastrophic results.

The damage to the primer thing has been reported before, but I’ve only seen it in reference to rounds used in AR style guns. The free-floating firing pin hits the primer and causes the damage over time. I’ve never before seen a warning about pistols or other guns with firing pins that don’t hit the primer.

In any event, the reported incident just demonstrates that there’s no need to chamber cartridges at full speed in “administrative” settings. To reiterate, that will damage hollow point or soft point bullets as well.

And FWIW, it’s always interesting to me to see how people will, without hesitation or question, accept a claim from a manufacturer that something like a misfire was supposedly due to operator error rather than a one in a million product defect. Factory ammunition, even the top of the line premium stuff, is not perfect. That’s why we learn and practice malfunction clearing procedures.

This picture is of three Winchester Ranger T-Series 357 SIG cartridges. The one on the left is a good round. The two on the right were taken directly from a new box of ammunition. The cases of those two were deformed to the point that they could not be chambered. Brand new, top tier ammunition that costs about $1.50 a round (when available).

I’ve never personally seen setback with my own ammo but have seen it happen with folks who consistently chamber and re-chamber constantly like everyday after carry etc.

I have always moved any unchambered round to the bottom of the magazine to limit this. That said I rarely do this unless I am dry firing that particular weapon so even without my routine my rounds wouldn’t see a ton of re-chamberings.

When I was still working I would have hundreds of employees that needed to qualify each year.
I would check everybody's gun, holster, and mags/speedloaders.
I would spot quite a few rounds that were out of spec just by looking at them.
Most were the first round in a semi-auto magazine.
The employees would chamber the first round at the start of there day and eject it at the end of there day. The constant chambering everyday of the first round would slowly drive the bullet back into the case over the years span.
Also many employees would drop the round when clearing the gun. Since the bullet end of the cartridge is much heavier the rounds would always fall bullet first thus aiding the bullet to be driven back into the case.
The same problem occurred with revolver shooters. The employee would load and unload into a speed loader each day. Many times the employee would fail to lock the ammo into the speed loader and the rounds would all fall out onto the concrete floor.

quote:

Originally posted by armored:
Since the bullet end of the cartridge is much heavier the rounds would always fall bullet first thus aiding the bullet to be driven back into the case.

Um ….
The bullet’s being heavier may cause the cartridge to rotate bullet down when the cartridge is held loosely with the fingers, but once it’s dropped, light and heavy all drop at the same rate.* That was demonstrated at least as far back as by Galileo. If it’s dropped base first and doesn’t rotate/tumble in its fall, the base will hit first.

*(Disregarding air resistance which would have no meaningful effect in this situation.)