Why you shouldn't cycle rounds multiple times

[jdege]

Thoughts on press checking and its impact on set back or primer separation?

My thought is the same. Whether the cumulative effect of press checking might impact set back won't matter, if you shoot out your carry ammo every month or so.

[Seismic Sam]

Well, this is very interesting news to me. Never heard of primer compound breaking down due to repeated shock (in the form of repeatedly chambering the round) before. Never heard about it before, never read about it before.

[AFTERMATH]

Well, this is very interesting news to me. Never heard of primer compound breaking down due to repeated shock (in the form of repeatedly chambering the round) before. Never heard about it before, never read about it before.

Seems plausible - Given hundreds of cycles...
I would guess too, that in most incidents it goes unreported. How many people actually send in a dud, looking for a non-conformance report?
Most don't even send in their FTF's - And the few that do, just send them back for replacement/refund.

Thoughts on press checking and its impact on set back or primer separation?

My thought is the same. Whether the cumulative effect of press checking might impact set back won't matter, if you shoot out your carry ammo every month or so.

The set back generally results from the bullet contacting the feed ramps and/or barrel.
When you're press checking, the cartridge doesn't leave the chamber. So, unless you're barrel has a really short throat and the bullet engages the rifling when chambered, I don't think you'd have to worry about set back. As far as primer compound breaking up - letting the slide forward a quarter of an inch isn't going to create nearly as much force as dropping the slide from it's locked back position. I sure as heck wouldn't worry about it.

[EJSG19]

Thoughts on press checking and its impact on set back or primer separation?

My thought is the same. Whether the cumulative effect of press checking might impact set back won't matter, if you shoot out your carry ammo every month or so.

Wondering how a press check would have an effect anywhere near that of a full range of motion slide slingshot? 1. If you get bullet setback from a simple press check, how? Does your bullet contact the lands upon chambering? If not I don't see there being anywhere near enough inertia to cause setback. If so, that gun needs a gunsmith asap.

Primer separation: this happened once in this article with apparently NO other documented occurrences. I guess I don't see primer separation as a top priority to worry about? I have had several primers with faulty anvils brand new out of the package. Seems pretty slim that the among company could track the cause of the bad primer to repeated chamberings honestly...

[kerns bbo]

Should setback really be an issue if your gun is feeding properly? Yes, if the bullet hangs it can cause some serious setback. But if the round is not chambering properly you would not be using that gun/ammunition for carry.

I did a quick test with a Kimber Ultra CDPII and Federal 230g Hydra-shock JHP. New cartridge oal started at 1.211 inches. After 10 cycles it was at 1.201, 20 at 1.198, and 30 at 1.197. I really don't think that 0.014 will cause an overpressure.

[Seismic Sam]

I agree that it's a very minor and unlikely failure mode, it's just that I had never heard of it from any source, including all the reloading manuals I have accumulated over the years. As far as reloading defense ammo, I load the mag all the way up, hold the gun with the slide open pointing down (and not at my foot!) and drop the round into the chamber, and then let the slide snap home or ease it forward by hand.

[jshuberg]

I was under the impression that dropping the slide on a chambered round could result in the extractor damaging the case rim. Doing this too many times could result in a FTE or double feed malfunction.

[Seismic Sam]

I was under the impression that dropping the slide on a chambered round could result in the extractor damaging the case rim. Doing this too many times could result in a FTE or double feed malfunction.

I have heard that before from somebody else, but at least in a 1911 I've never seen any evidence of this happening, and I can't imagine the lateral spring force of the extractor is so high as to deform the brass. I mean, you can depress the extractor hook with your finger or a tool if you want to, so it's hard to imagine the extractor snapping over the brass causing any damage. Now I HAVE seen effects from a high pressure load that wouldn't let go of the chamber walls when the slide started to pull back, and the PULL from the extractor hook damaged the rim of the case, but that's an entirely different matter.

In addition, I have never seen anything written that says explicitly that in normal chambering that as the round comes up out of the mag, it will place itself flat against the breechface and slide up under the hook. The 45 case is pretty damn big, and it has to jump up from the mag onto the ramp nose first and then enter the chamber and straighten out as the slide is closing on it very fast, and does anybody really know if the case is dead parallel to the breech face BEFORE it is on the same axis as the bore?? For a half inch wide case, it has to be parallel to the bore axis about 1/4" below the bore axis for the case rim to slide under the extractor, and I'm having trouble visualizing it always happening repeatedly that way 100% of the time. So if anybody has some hard data in writing or slo-mo video of a 45 case chambering to show how it works, I'd be interesting in seeing it.

And to repeat, how do you get the round perfectly on axis with the bore when it is 1/4" BELOW the bore axis itself, meaning that it has not yet entered the chamber?? Either the extractor hook snaps over the case rim as the case rotates up into place on the breech face, or the case head has to be dead flat against the breech face below the bore axis to slide up under the extractor.

[Snowgun]

I posted a study I did on chambering setback on this board a couple years ago.

Results: fmj is dangerous after about 10 or so chamberings, but high quality, crimped SD ammo didn't setback appreciably after many cycles, like 90

[plblark]

I had an issue with Cor Bon 45 +P VERY early in my adventures with guns. IDK how many times it was cycled but there was OBVIOUS setback. the crimp wasn't terribly tight on the remaining rounds I checked.