Inherently reliable/unreliable auto pistol cartridges?

Your point, I think, is that it's too easy to blame the ammo when the gun might be at fault...
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No, my point was that it is the combination of the gun and the ammo that can be to blame, not either the gun or the ammo (although this does happen often, perhaps more often)

Why focus on "pocket autos?" You seem to be arguing that the gun's design (locked breech or blowback) and size are key factors in assuring reliability.
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No, what I was arguing was that since the .22LR is found in all sizes and styles of pistols, even if its failure rate were identical with something else, it would seem to be greater.

The .22LR has several things stacked against it when it comes to reliability in an autopistol. First is the "inherent" failure rate of rimfire ignition. Second is the round's size, design, and construction, and third are the guns themselves.

So, the failure rate to cycle reliably in all guns is lower than centerfires.

One fellow once said that he believed that the only reason the .25Auto (.25ACP) still existed was that, unlike .22s they almost never jam. He was referring to the tiny pocket autos, and FMJ .25ACP ammo. Quite simply, while the lead bullet of the .22 might do more damage the FMJ .25 in the bad guy, being able to reliably count on getting A bullet into the bad guy counted for more.

My story about the S&W 41 the Ruger & the CCI blazer was to illustrate how an gun (even a high end gun) can get ammo it chokes on, and that same ammo can be fine in a different gun. And that different gun might choke on ammo the first gun eats like candy. .22s are like that.

Most of them run fine on almost everything, some don't.

I'll grant you the cartridge has a lot to do with reliability, but the gun plays its part too, and that part is not insignificant.

I agree a bottle neck cartridge would enter the chamber with greater ease but beyond that I think the 9mm is superior. The main body of 357 Sig is about the same as the 40S&W, the more surface area of the cartridge makes for higher force needed to chamber IMO.
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While you can measure the difference in the surface area of the case bodies, and calculate the difference in the friction between the 9mm Luger and the .357 Sig, I believe that while measurable, the difference in friction between the two is, in practical terms, insignificant.

Bottle necked rounds feed well because they are essentially tapered cones going into a round hole. Any errors in alignment are overcome by the centering effect of the taper. When you are loading a straight case, at speed the way an autoloader does, you must obtain, and maintain very precise alignment of the round so it will feed smoothly into a hole only a very few thousandths of an inch larger than the ammo itself.

The larger, and particularly longer the case is, the more important the alignment and maintaining it through the feeding cycle, becomes.
 
“While you can measure the difference in the surface area of the case bodies, and calculate the difference in the friction between the 9mm Luger and the .357 Sig, I believe that while measurable, the difference in friction between the two is, in practical terms, insignificant.”

Once the chamber becomes fouled with smoke/powder residue and tiny bits of brass/copper I would think the larger cartridge would be more difficult to fully seat. :D
 
Once the chamber becomes fouled with smoke/powder residue and tiny bits of brass/copper I would think the larger cartridge would be more difficult to fully seat.
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I suppose it would be. But, observed results do not show the small difference to be significant. Remember that you are looking at a small weight, less than an ounce, being fed with several pounds of spring pressure.

And, while powder fouling can build up rapidly is black powder arms, smokeless power (even the dirtiest) produces much less residue.

If the difference in friction between the 9mm and .357 Sig(.40S&W) due to the difference in the case body size, were significant, then the .45ACP would be worse, and observably, it is not. Clean or dirty chamber.

Sure, you can shoot a pistol enough that it gets dirty enough to jam, but if friction due to the size of the case were the dominant factor, you would see .45s sieze up before the .40 and the .40 before the 9mm.

In observed behavior the opposite almost seems true. It is certainly true with bullets and barrels. The larger round simply runs over and ignores crud that affects smaller rounds. In a barrel, a small imperfection that might send a .22 bullet off is of little, if any concern to a .45.

The friction of the case is one concern in the design of firearms, and they are designed to have more than enough power in their feed cycle to overcome this.

And until conditions become extreme they generally do.
 
How about looking at where the cartridge headspaces? The bottleneck cartridge headspaces on the shoulder/taper while the straight wall cartridge headspaces at the case mouth. The latter case mouth having less area would be able to push fouling material away better I would think.
 
I suspect that fouling that makes it's way back to the chamber has more to do with how a given chamber fits to the cartridge being used than whether the chamber is for a tapered, bottle-neck or straight-walled cartridge.
 
“I suspect that fouling that makes it's way back to the chamber has more to do with how a given chamber fits to the cartridge being used than whether the chamber is for a tapered, bottle-neck or straight-walled cartridge.”

I believe you’re saying a closer fitting cartridge to chamber tolerance would keep the chamber cleaner longer. Such a firearm would also likely have less free-bore and other features to enhance accuracy. I believe such an arm would be reliable but the round count would be more definitive/specific before maintenance (cleaning/lube) would be needed.
 
After firing the case expands against the chamber, doesn't it? I would think this would keepmost fouling out off there.
 
745SW said:
Such a firearm would also likely have less free-bore and other features to enhance accuracy. I believe such an arm would be reliable but the round count would be more definitive/specific before maintenance (cleaning/lube) would be needed.
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I've seen additional freebore (the space between the chamber and where the rifling begins) mentioned as a way to increase velocity -- by allowing a bullet to be set less deep in the case, allowing more powder to be used in the small added space.

I've not previously seen "less freebore" mentioned as a way to increase accuracy. How does THAT work -- in theory?

Guv said:
After firing the case expands against the chamber, doesn't it? I would think this would keepmost fouling out off there.
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I'm guessing -- as I've never really seen this discussed, but...

The force of the powder explosion doesn't just go down the barrel; some of it has to go to the rear, as well... Some of the powder residue is probably in the case and barrel as the case is extracted, and trails behind the case and "paints" the chamber and open slide area too. I've noticed that some ammo is much dirtier than other ammo...

In another discussion on this forum we were talking about blowback guns, and the H&K P7 came up. It's gas-retarded system, but doesn't have an extractor. That design uses a fluted chamber to retain the round and the force of the explosion also helps eject the round from the chamber... clever design.
 
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My P7 has an extractor, but all auto loaders only use their extractor when extracting an unfired cartridge.
The empty brass pushes the slide/bolt open , the slide/extractor does not pull the empty brass from the chamber when firing.
 
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My P7 has an extractor.
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Mine did as well. But it was always my understanding, they will function without them.

Then again, anything I had HK, always chucked the brass into next week. :)
 
Another thing that isn't discussed in this thread is the material of the shell casing. Brass "slides" better into a chamber than steel cased ammo. Steel causes more friction - and expands more after firing so extraction of steel vs brass can be more difficult.
 
.32acp rimlock

I have experienced numerous .32 rimlock stoppages with my kel-tec, but only with hollow points. Very annoying - I have to take the floor plate out of the magazine and dump the rounds to clear the jam. HP .32 is more likely to rimlock because it is shorter ammo. I have never had an issue with .32 fmj. Kel tec makes a magazine spacer accessory insert for hollow point ammo, but I have not tried it. I just shoot full metal.
 
Re: other guns only using the extractor to extract unfired rounds.

I've had several Beretta Tomcats, and they don't have extractors. Period. And they extract just fine if the round is fired.

I suspect, however, that the extractor plays a bigger role in extraction with some guns -- or broken or chipped extractors would NIT cause as many problems as them seem to cause with rounds that ARE fired.

Maybe the extractor just keeps the round positioned against the breechface until it strikes the ejector* -- and the extractor really only guides it to that point?

This little bit of gun design remains a bit of a mystery for me.

*rewritten to correct the dumb typos...
 
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I've had several Beretta Tomcats, and they don't have extractors. Period. And they extract just fine if the round is fired.
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I had a couple of 21A's as well, and they worked OK, up until they started getting dirty, then, not all that great.
 
Magazines

I am surprised no one has mentioned magazines as a problem. It is my understanding that in the 1911 platform that magazines give more stoppage problems than anything else.
 
I am surprised no one has mentioned magazines as a problem. It is my understanding that in the 1911 platform that magazines give more stoppage problems than anything else.
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Could be, but that's arguably not a problem of the 1911 design or the .45 ACP round used. When that problem raises it's ugly head it's typically due to poorly-made or cheap-knock off magazines.

Milspec mags that are truly mil. spec. seem to work well, as do any number of well-made mags sold by Metalform, McCormick, Wilson, etc., etc.
 
It is my understanding that in the 1911 platform that magazines give more stoppage problems than anything else.
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This issue is NOT restricted to the 1911, it happens to virtually ALL semiautos, pistol or rifle.

Statistically speaking, problems with the feed cycle (that are not the fault of bad ammo) are most likely something with the magazine.
 
“I've not previously seen "less freebore" mentioned as a way to increase accuracy. How does THAT work -- in theory?”

I Believe freebore is one of the differences between a military arm and a sporting arm. The military arm needs to be more tolerant of debris buildup (a margin of safety) while the sporting arms focus is accuracy, less freebore. Less bullet jump before hitting the rifling means better consistency I believe.
 
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