Chamber Check your ammunition

Let me see....
The slide slams forward ramming the round into the chamber with quite a bit of force. Enough force to chamber even a slightly "tight" fit (think match grade chambers).

When the round is fired the force of the exploding gasses expands the brass to fit the dimensions of the chamber making for a tight fit yet the extractor still pulls it out. And pulls it out while still hot and expanded....

So... without trying to be a smart arse and actually wondering while sincerely wanting some actual factual answer....

Assuming quality ammo/gauged reloads is under discussion....

Other than knowing the round will drop into and fall out of the chamber under conditions that don't even come close to the actual working conditions during cycling.... what gain is there by doing a "chamber fit"?

Bikenut said:

When the round is fired the force of the exploding gasses expands the brass to fit the dimensions of the chamber making for a tight fit yet the extractor still pulls it out. And pulls it out while still hot and expanded.

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The cartridge had better be working in the elastic region of its stress-strain curve, while under pressure, so it can recover its circumference when not under pressure. There is not a lot of section density in a cartridge to allow plastic flow deformation. That's a kaboom.

Herr Heckler Koch said:

The cartridge had better be working in the elastic region of its stress-strain curve, while under pressure, so it can recover its circumference when not under pressure. There is not a lot of section density in a cartridge to allow plastic flow deformation. That's a kaboom.

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Ah, thank you, was about to say the same thing. The cartridge (hopefully) recovers its original diameter (+/- a thousandth or so) almost instantaneously after firing.

Now, what manufacturer in their right mind puts a match chamber on a weapon? Target gun, yes, but a weapon? Probably a marketing hype to appeal to the general public?

Seems sexy, but not very reliable in adverse conditions.

Kalashnikov had the right idea- a certain amount of 'looseness' increases reliability.

fire suppressor said:

LOL thank you I just had a ah hub moment!

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Not a problem - I am a daily practitioner of senior moments myself.

Herr Heckler Koch said:

The cartridge had better be working in the elastic region of its stress-strain curve, while under pressure, so it can recover its circumference when not under pressure. There is not a lot of section density in a cartridge to allow plastic flow deformation. That's a kaboom.

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Yes, I understand that there is some recovery of circumference as the pressure curve decreases... however... the brass is still hot and has expanded a certain amount simply from the heat. That heat induced expansion means the casing now has a larger circumference than it did when it was cold and being chamber checked to see if the cold round would fall out.

So what does the round falling out when cold prove about the ability of the extractor to pull the casing of the now fired, and hot, round?

I guess I just don't see what a round falling in/falling out of the chamber when cold has anything to do with the round chambering/extracting under real working conditions?

Again, we are assuming (yeah, I know what the word means) we are talking about quality ammo/gauged reloads.

The units of both strain and thermal expansion include ∂ℓ/ℓ (that's differential ell over ell). Compare the magnitudes.

bikenut, my thinking is....if the round will not easily go in and fall out of the barrel when tilted, then the round is not safe to fire, that minor expansion during firing could cause a tight fitting round to get stuck in there, putting the gun, and possibly you out of commission.

thats just my thought process though, checking for "bad" rounds, bulged casings, setbacks and all that should be done on carry ammo i think

Herr Heckler Koch said:

The units of both strain and thermal expansion include ∂ℓ/ℓ (that's differential ell over ell). Compare the magnitudes.

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So what are you saying? That there wouldn't be a noticeable difference, or a difference that might make a difference, between a cold round and the hot casing of a fired round? If the cold one feel out then the hot one should also fall out?

If so... or even if so... what has that got to do with the fact that the casing may or may not "fall out" after firing but never gets the chance because it is forcibly pulled out by the extractor anyway?

And even if a round "falls in" that is no guarantee a failure to feed won't happen. Not to mention that the rather violent action of the slide can still successfully chamber a tight fitting round.........

I'm not knocking "chamber checking".... I'm just want someone to provide some kind of actual factual benefit because without facts I'm not going to waste my time fiddling around just to get a nice warm "feeling" because my (quality ammo!) rounds fall in and fall out of the chamber under conditions that don't even come close to the actual conditions that round encounters during the gun's normal operation.

No, I do not do that as I have never had an new out of the box pistol cartridge have this problem and I only shoot new out of the box SD ammo. However, I have had new target ammo that is slightly short and not feed because of that (nose dived into the ramp). So, when I open a new box of SD ammo I do use the edge of a level across all the rounds vertical, horizontal and diaganol across and look for any that are obviously off and then swap out some rounds out of a box I have already checked/shot without any issue and check again in case the whole box is off. Just takes a few minutes. Not terribly scientific but the times I had issues, the ammo was off enough that the above technique showed a little daylight between the square and the rounds.

And no, I don't bother with checking practice ammo, but I have become conscientious about knowing in what order I load practice ammo out of what box (or just what box in the case of non-tray loaded ammo such as 100 rd WWB) in case I do have another problem so I can more quickly track it down. The first time it happened it took a day for me to think it thorugh enough to track it back effectively to a particular row in a particular box.

It prevents you from causing a jam when you need to shoot someone, by ruling out one more potential problem.

One step in reloading for instance, is applying a flare to the brass. This bells the case mouth of the brass a hundredth or so, (a vast distance in a gun), so that you can seat the bullet more easily, and avoid shearing as the bullet enters the case. If you forget to remove the bell in the final crimping stage, the bullet won't chamber properly. This crimp is so slight, that you wont see it unless you look for it, or when the case goes half way into the chamber and stops.

Im not sure if the factory does this belling and crimping stage, or something similar, but it can cause problems for the handloader.

lil_freak_66 said:

bikenut, my thinking is....if the round will not easily go in and fall out of the barrel when tilted, then the round is not safe to fire, that minor expansion during firing could cause a tight fitting round to get stuck in there, putting the gun, and possibly you out of commission.

thats just my thought process though, checking for "bad" rounds, bulged casings, setbacks and all that should be done on carry ammo i think

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How many bad rounds have you found with quality ammo?

I got a box on SD ammo once without a bullet in the case. I've seen bullets loaded backwards in the case, and heard of primers missing, or installed backwards. Some people weigh each round to make sure the powder is in the case.

Bikenut said:

So what are you saying? That there wouldn't be a noticeable difference, or a difference that might make a difference, between a cold round and the hot casing of a fired round?...

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Am I the only one who gets them red hot with a propane torch before chamber checking them? You guys are lazy!


Okay, seriously:

I don't require my reloads to FALL in and out of a gauge/chamber. To me, the gauging is to determine if there was an unseen/unfelt error or bad component/procedure during reloading. Primer seat is checked by visual and tactile methods at the same time. Experience has taught me an acceptable level of resistance.

Honestly, I don't gauge factory ammo if from a known high-quality source. And I guess this was the real question in the thread. But since I am one who usually carries my reloads, it did seem worth mentioning because my defensive rounds have indeed been gauged.

I wonder just how "match" an XD(m)'s chamber really is. I didn't mean to imply that it would be like a Freedom Arms revolver, just that that is what I THINK of when I hear the term.

As for bullet set-back, I once bought two boxes of Blazer .40 from Midway. When they arrived (in an undamaged box with other stuff), one of the boxes of Blazer had been crushed in the corner, meaning it had to have been that way before packaging. I'm not one who cares about the box, but three of the .40 rounds in that corner had varying levels of significant bullet set-back. My thoughts were on the liability of Midway for shipping it! If I didn't know better, and had shot one, and IF it blew up a gun...

As for rounds that fail the case gauge (it happens sometimes), I put them in a known practice/training pile. They get mixed into ammo that I am practicing with. SOMETIMES, one of them will cause a malfunction, which is great for training.

Bikenut said:

How many bad rounds have you found with quality ammo?

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since ive ran through less than 100 rounds in my handgun so far, so none. but i have found one surplus round before for my sks(7.62x39) that had a tight fit, i fired it(this is what caused me to start checking) and it got stuck, had to tap it out with the cleaning rod. i checked all my ammo after that, and found a single 7.62x54R silver tip that was bulged too, so i discarded that one.

we can blame the soviets on loose tolerances for those rounds, but one can never be too sure i think.

im sure that finding a bad case is an extremely rare occurrence in modern ammo that is of quality. but checking gives one less variable that could cost somebody they're life

Only 100 rd, what you carrying? I just passed the 10,000 mark on the little XD.

its a star firearms firestar M43(9mm)

just got it a few weeks ago, put through 2 boxes so far to test for any issues with it(btw, pro mag magazines SUCK) and now im carrying 25 or so of the same rounds. and ive got an additional 75 rounds in the ammo box waiting to be shot.

going to get alot more soon so i can run alot more through, but because of holidays and other things, havent worked much since christmas so i havent had the money. this coming week looks to be a 40-45 hour week so ill have the $ to drop on a few hundred rounds and donate some more to cadl after child support is payed.

Good to hear. Maybe you should think about handloading.

TheQ said:

....

I rotate my ammunition monthly through different magazines (help prevent spring wear from being constantly compressed, if such a thing exists (it's been debated)). ...

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http://www.migunowners.org/forum/showthread.php?t=160752

Bikenut said:

Other than knowing the round will drop into and fall out of the chamber under conditions that don't even come close to the actual working conditions during cycling.... what gain is there by doing a "chamber fit"?

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A round that is misfired such that it doesn't simply fall out may mis-feed when it comes time to use it.

Bikenut said:

How many bad rounds have you found with quality ammo?

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I had one Winchester White Box (admittedly range ammo, but still manufactured by a large, reputable manufacturer) round that failed to load because it was a malformed case.