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pmc 40sw case head failure

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so at the match last sunday, this happened

post-53161-0-40394100-1464176886_thumb.j

the head blew clean off.

i chalked it up as a fluke, but then it happened again the next weekend at practice.

both times, pmc cases

post-53161-0-68169200-1464177033_thumb.j

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so i collected all my brass, went home and inspected them

out of about 100 pmc cases, i found about 6 that were bulgier than normal.

i look inside the cases and i'm finding cracks where the bulges are

post-53161-0-18055500-1464177301_thumb.j

i cut one in half to see how deep the crack goes

post-53161-0-47478300-1464177350_thumb.j

has anyone seen this kind of failure before?

i don't believe they were fired out of battery

the load is ibejiheads 180gr rnfp with 4.6gr of wst at 1.185 shot out of an sti edge

Edited by inline4

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I have had the same problem with PMC brass blowing up in my XDM, and cracking the frame. Took the third failure to figure it out. It always happened to me with a 180 grain lead bullet, and Unique powder. I will bet the farm your velocities were matching mine. Did not happen with plated or any other powder. My solution was to not use Unique or lead loads in .40. I never did figure out why the PMC was separating, but I have never had the problem since.

I still remember the stinging smack to my hand when it happened.

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I don't know about the rest of them but that first picture was fired out of battery. There is no question about that.

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I don't know about the rest of them but that first picture was fired out of battery. There is no question about that.

i'm relatively unexperienced so please correct me if i'm wrong.

i've heard that 2011 is pretty much impossible to fire out of battery.

i've tried it with my gun, i can pull the slide back about 3mm and still launch a pencil across the room, but at that point, the barrel still appears to be locked up to the slide.

if i pull the slide back any further, i can no longer pull the trigger due to disconnect.

and also the barrel starts to cam down, so the firing pin don't line up to the primer anymore.

also, i fired about 300 rds that night, most of the extra bulgy cases were pmc, with a couple of oddball cases.

it makes me think the cracks are developing inside the cases from be fired and reloaded, which eventually weakens the case wall at that area and causes the bulge to get worse.

post-53161-0-96819600-1464181046_thumb.j

pmc on the right, win case on the left for comparison

the bulge on the pmc appears to be the same height as any of my other brass that i've shot that day.

only pmc cases are getting the occasional extra bulginess.

and extra bulgy always correspond to the crack inside.

when i do the plunk test, the area exposed at the feed ramp is only about half the width of the bulges.

could it be a gun problem, like it is unlocking too soon or something?

gun seems to be running fine otherwise

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post-33742-0-88494300-1464266906_thumb.j

Here is a picture of mine, and I guarantee it was not fired out of battery. No other brand of case blew like this with exactly the same load, and the powder was not exceeding max levels. I have never gotten an answer from PMC, Alliant, or Springfield on why this is happening. I just ended up pulling about 400 rounds and will never use the Unique and lead 180 combo in .40 again.

Edited by mont1120

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attachicon.gifBlown case.jpg

Here is a picture of mine, and I guarantee it was not fired out of battery. No other brand of case blew like this with exactly the same load, and the powder was not exceeding max levels. I have never gotten an answer from PMC, Alliant, or Springfield on why this is happening. I just ended up pulling about 400 rounds and will never use the Unique and lead 180 combo in .40 again.

looks exactly like mine.

almost looks like the case was assembled from 2 pieces and somehow welded together, contrary to that starline video that shows how brass is made.

when you had your blowouts, have your brass been reloaded multiple times?

was it range pick up that had been shot from a glock or anything like that?

strange that it only happens with lead bullets. I figure pressure is lower with lead at a given PF, right?

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Both pics really look like it's 2 piece brass.

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It was plain old range brass, could have been shot with a Glock, but the rounds fed fine, so no bulge could have been there. Again, in my case it was a medium charge of Unique, and only with lead. Plated bullets from Berrys caused zero issues.

As is the case from all range brass, how many times was it fired? I have no idea. I really doubt it was more than once since it came from target shooters, not competition people. I would bet the farm I could load the same round up and blow my XDM. I agree with all here, using lead should lower pressures, all I can figure is PMC brass is slightly thicker then others, although I do not know that for fact.

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. I agree with all here, using lead should lower pressures, .

I believe that under certain conditions it can raise pressure, as it seals in the bore tighter causing a spike when it first engages the rifling.

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It was plain old range brass, could have been shot with a Glock, but the rounds fed fine, so no bulge could have been there. Again, in my case it was a medium charge of Unique, and only with lead. Plated bullets from Berrys caused zero issues.

As is the case from all range brass, how many times was it fired? I have no idea. I really doubt it was more than once since it came from target shooters, not competition people. I would bet the farm I could load the same round up and blow my XDM. I agree with all here, using lead should lower pressures, all I can figure is PMC brass is slightly thicker then others, although I do not know that for fact.

PMC is thicker brass! But reading the post, Could it be a tight chamber and the thicker PMC brass causing the blowouts?

I use PMC brass all the time in 40 and 45 and have never as yet had a blowout.

Edited by ghost21

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after further inspection, I've found that for 40sw, pmc has at least 3 different headstamps.

there's .PMC. with the 2 dots and the legs of the M parallel.

these seems to be the troublesome ones.

there's .PMC. where the legs of the M is slanted, and then there's slanted M with no dots.

the latter seems to be much improved. where the wall meets the web, it's nicely radiused, whereas the other 2, it's more of a 90° angle.

it almost seems like pmc knew of an issue with their brass and have made changes.

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Case head failure in .40 is nothing new and generally leaves the case in the chamber and the back of the case pops off. When you see the back of the case swelled up all the way around that part of the case was unsupported by the chamber when the round went off. There is no augmenting this fact. If it has a guppy look then it was unsupported by the feed ramp portion of the chamber so one side will be swelled but when it goes all the way around the back of the case and is that large the reason for the case head separation is no support in that area of the case. I have seen high primers get detonated before the gun could reach battery that looked just like the pictures. Unless you can figure out how a case can swell the entire circumference while sitting in a supported chamber, out of battery is the only answer I can see on 2 of the pictures here.

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I understand that 40sw has that reputation for KBs.

what is interesting is how cleanly the head sheared off.

are you saying this is normal?

because I asked around at the match that day, and it seems no one has seen that before.

I understand that the case bulged, therefore it must have been lacking chamber support.

however, both times, the primer shows a clean firing pin hit right near the center.

doesn't that rule out a high primer?

imho, that also rules out OOB, because the 2011 cannot fire OOB.

is there no other possible way brass can bulge all around like that?

again, not trying to argue with anyone, just trying to learn.

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What is you over all length? Maybe the cartridge is ever so slightly too long.

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I think I have some 9mm cases to re-inspect...

there is not a lot to this. Brass will only stretch so far.

If you look at the bulge of the case wall of the failed case,

it is a lota stretched or bulged. the metal of the case will fatigue somewhere, given that bulging.

the photo looks like the brass formed to the shape of the ramp.

If you can keep track of your brass, watch it and inspect for that cracking.

I would think a couple of firings, but after that, I am not at all sure.

the bag of starline brass I have (and do not use....) says they guarantee it for 5 firings.

if you can track the brass let us know how many times before you get cracking?

Have a picture of a case after you run it through this gun?

... the bulgier than normal one perhaps?

I just noticed you posed the other set... didn't realize it was you.

miranda

Edited by Miranda

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