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lamarbrog
5 March 2012, 18:42
http://i72.photobucket.com/albums/i190/Lamarbrog/DSCN1081.jpg

While cleaning the range a couple weeks back, I stumbled upon this cartridge. I'm not exactly sure what happened to it. I think it was involved in some type of malfunction, may have been run over by a machine used to clean the range, and ultimately was trampled on when it got caught beneath a grate. It was in sad shape, as the picture shows.

My associates saw it, and most were convinced it was unsafe. While I generally would probably throw it away, I disagreed that it was not safe.

So, not being one to make unsubstantiated claims, I volunteered my rifle to prove it. I loaded the cartridge seen above into a magazine, locked the magazine in on an open bolt, and pressed the release. The cartridge chambered most of way, but would not lock into the chamber. I mortared the rifle to extract the cartridge, and repeated the procedure. This time, it managed to chamber.

I made certain my eye protection was adjusted, held the rifle at arms length, pointed down range, took a deep breath, and squeezed the trigger. It fired. The case extracted and ejected as normal. Inspection showed that the case fire-formed to the chamber and looked like any other piece of scratched-up range brass. You'd never have known it was so mangled.

Just thought it was interesting how tolerant these rifles are to having some damaged ammo run through them. Pretty amazing if you ask me.

AR-10
5 March 2012, 21:21
I would have thrown that thing in the trash.

I bought 1000 rounds of green tip in a box once, a couple dozen had some very minor dents (nothing like the one you found).

I put them in their own little pile and consider it "absolute last resort" ammo.

lamarbrog
5 March 2012, 21:32
I would have thrown that thing in the trash.

I bought 1000 rounds of green tip in a box once, a couple dozen had some very minor dents (nothing like the one you found).

I put them in their own little pile and consider it "absolute last resort" ammo.

I have fired literally hundreds of rounds of ammunition with "minor dents" (such as those seen when bolt lugs hit a cartridge along the side during certain malfunction) and have never had any sort of failure when shooting it. Obviously, this should not be considered primary defense ammunition, but if it ever comes to the point where you've only got a little ammo left and it is damaged... you can shoot it without generally having to worry that it might cause injury to you.

Some people will refuse to shoot ammunition even just for practicing at the range if it has the slightest blemish. Minor bits of corrosion, a flaw in the alloy, a small dent or ding. There seems to be this idea in the minds of many that if ammunition is not absolutely pristine, that it is dangerous and likely to destroy the weapon in some way. My point here is that ammunition has to be really, really bad before it would likely cause damage to the firearm.

zero7one
6 March 2012, 10:34
Though I would have had reservations of firing that round, I appreciate the fact that you "experimented" to see if the round would have actually worked as designed. As for brass deformities, as long as the brass still holds a true line and it will chamber, the round "should" still perform. I however would never fire a round that had damage or deformity to the actual bullet itself.

As with your round above, with such a sharply angled dent, the possibilities for a crack in the brass are possible. If your brass is cracked, it could lead to other complications like the brass actually fragmenting, thus causing a whole new world of problems when the propellant is looking for the path of least resistance to travel.

markm
8 March 2012, 09:50
I'd have pulled that round appart and used the bullet. But yeah... if a round will chamber, any dents will quickly fire form out of the case.

Casull
9 March 2012, 11:32
I'd not fire that, but I know for sure that dented rounds will fire just fine expanding the casing back into "shape". I have gopro footage of me short-stroking a round which left a good dent in it.. I re-chambered it, and fired. Worked fine. Yadda yadda.

Obviously we don't want to get ridiculous, though.

Zeeba
13 October 2012, 12:42
That round probably wouldn't fit into the chamber anyway, unless you really rammed it home. Dents that deep had to have bulged out the case adjacent to the dents. It's best not to even try.

lamarbrog
13 October 2012, 21:50
That round probably wouldn't fit into the chamber anyway, unless you really rammed it home. Dents that deep had to have bulged out the case adjacent to the dents. It's best not to even try.

It fit into the chamber with nothing more than pressure from the buffer spring. It took a second try, but no force was required other than the force the action has.

It did bulge the case out adjacent to the dents, which is why it took a second try. The force of the action was not able to swage it entirely on the first try. Once it was chambered, though, it fired just fine.

Obviously, though, it is generally not worth the hassle. This was just a test of an unlikely extreme situation.

bigedp51
15 April 2013, 07:55
The problem isn't if you can force a dented case into the chamber, the problem is the reduced case capacity of the dented case and what the actual chamber will be. By just seating the bullet deeper into the case the chamber pressure can go higher than the rated pressure of the cartridge. I other words you will get a pressure spike higher than normal, in a car engine it would be like shaving the heads to increase the compression ratio. (decreasing the internal volume of the cylinders to gain more horsepower)

Below shows the difference between two brands of cases in their internal capacity and chamber pressure from Quikload software using 25.5 grs of H335. The chamber pressure will peak faster and higher (spike) with reduced case capacity and cause more bolt thrust which can damage your rifle. Bottom line small dents are not that bad BUT one like you have pictured should be unloaded and scrapped.

30.6 gr H2O 49,618 psi
28.0 gr H2O 61,987 psi

http://i122.photobucket.com/albums/o254/bigedp51/casecap_zpsb0f5b356.jpg (http://s122.photobucket.com/user/bigedp51/media/casecap_zpsb0f5b356.jpg.html)

lamarbrog
15 April 2013, 17:49
Fired just fine with no signs of excess pressure.

I've fired dozens of cartridges almost as bad as this one... never have run into a problem. Not going to stop shooting them now. Do you have any actual evidence that the dent does increase chamber pressure?

FortTom
15 April 2013, 19:38
I'm from KY, so I can say this...and get away with it. What's the last thing you here before a Kentuckian dies? "Hey Ya'll Watch This"!!!! And that's pretty much what I think about you firing that cartridge. Dent's yeah, I've fired dozens of rounds with dents, especially right on the shoulder. I think by it being so bad you had to force it in the chamber, you were asking to grenade your rifle, and maybe yourself and bystanders. I would bet you that pressures went through the roof, although now, neither of us can prove anything conclusive, except that it fired, and you still have a rifle. Don't take offense to my answer, because...well..you asked.

FT

lamarbrog
15 April 2013, 19:50
I'm from KY, so I can say this...and get away with it. What's the last thing you here before a Kentuckian dies? "Hey Ya'll Watch This"!!!! And that's pretty much what I think about you firing that cartridge. Dent's yeah, I've fired dozens of rounds with dents, especially right on the shoulder. I think by it being so bad you had to force it in the chamber, you were asking to grenade your rifle, and maybe yourself and bystanders. I would bet you that pressures went through the roof, although now, neither of us can prove anything conclusive, except that it fired, and you still have a rifle. Don't take offense to my answer, because...well..you asked.

FT

The thread title was a rhetorical question.

I'll bet you pressure was hardly affected in any way. The lack of an pressure signs on the fired case indicate that if there was an increase in pressure, it was not substantial.

Bystanders did not exist.

I'm not particularly worried about "grenading myself" with an AR15. Having seen numerous catastrophic failures in AR15s, I have never seen anyone experience a serious injury... it's a pretty safe rifle to blow up.

tpelle
27 April 2013, 18:06
I agree that minor dents aren't an issue, and that they will fire-form back into shape. The other evening, however, I was competing in a highpower match, and was manually loading a sighter round in my AR before the sitting rapids. I fumbled the cartridge, and when I dropped the bolt I had a bolt over base jam. I cleared it, but the case has a big gouge or scratch in the side where the bolt closed on it and some brass is shaved off into a little curl. That one is going to get pulled apart and definitely NOT shot, as I figure the missing brass creates a weak spot.

I guess the chamber probably would support the case sufficiently even where it's been weakened, but I don't really want this case recycled back into my reload rotation.

tappedandtagged
15 December 2013, 11:46
I'd be more worried about case separation which would result in the back half of the case being extracted leaving the bottle neck potion forward of the mangled part being left in the chamber. Personally, I would have pulled the bullet and reloaded it and tossed the case in the pile to be taken across the scrap metal scales.

But, I'm glad you tried it and I'm glad it worked out well if nothing else but for curiosity's sake.