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Help me understand this ruptured case


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We had our first shots today with the new PSA 16" pcc. At home, before going to the range, I tried chambering a round and I didn't fully let go of the charging handle which caused the round to not go into battery, and it was badly damaged. I did it again and same thing, then I remembered you have to pull it all the way back and completely release, just like most pistols. Then I could chamber a round fine.

Anyways, I forgot to tell that to my son, and on the first round from a fresh magazine, the pictured ruptured case happened. My concern is, is this normal to be able to drop the hammer with a round this far from being in battery, and is this something we are risking every time if the charging handle isnt completely released?

 

BTW, the case is swelled with a ring all the way around above the rupture, which makes me think it with lit off OOB.

 

The pcc ran flawless besides this round. acd7082f84f2ff65d13b253e353ddc6b.jpg

 

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I learned from reading here awhile back that blowback PCC ‘s will indeed fire when way out of battery. Not the same as regular AR’s. 
 Many many many PCC barrels have very short chambers, sloppy reaming, short lead, etc. this thing was way out of battery though. Any chance of a squib or other barrel obstruction? Sometimes they are virtually undetectable.

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This ammo plunk tests fine, its already loaded quite short for a CZ. And I really don't think there was an obstruction before this round.
If (1)easing the bolt forward instead of letting it slam home can damage the first round and (2) it can fire out of battery, then it seems like we will be risking this happening any time it isn't charged in a textbook manner.

So, I just tried something: I locked the bolt back, inserted a mag and used the bolt release to send the bolt home. On three rounds, this is what they look like after ejection. The bullets are seriously dented, and one casing is damaged at the crimp. The other two casings have faint lines in them. Bullets are 147gr brazos, which relatively soft lead. 2443720f6bf3faa2735a5c5f30fa5190.jpg

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What's the headstamp? I've seen this happen with "stepped" brass (has a step on the inside of the brass at the same level as your separation) Typical headstamps are "Ammoload", IMI, and a couple of others that escape me at the moment. I shoot 9 major and I cull that brass out during inspection and throw them into recycling. When PCC first became a "thing", there were a lot of malfunctions at matches, most of them involved jamming where the forward part of the case stayed in the chamber and the rear part was ejected. They were all traced to stepped brass. Could be something else, looking at you pictures, the dented bullets are troubling, but I would eliminate the brass brand as a culprit first.  First pic is an Ammoload cut open, second pic is a separated "Tula" case (I don't use Russian brass anymore for this reason). Good luck.

Ammoload 3.JPG

20190305_193335 (Medium).jpg

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I would get similar looking marks from time to time in my MBX using 135gr RN loaded to 1.12 inches. Switched to 115gr, kept the same OAL and haven't seen the feeding marks since. The 115gr bullet profile is slimmer and seemed to eliminate the issue.

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9 minutes ago, HoMiE said:

Bullet setback on a stepped case causing higher pressure, not oob. 

I beg to differ. Look at the case. If it had happened INSIDE the chamber, as you suggest, the case would not be splayed apart as it is. The chamber would have contained the rupture and the split would be more uniform....and the case would not be bulged all the way around as it is.

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8 minutes ago, GrumpyOne said:

I beg to differ. Look at the case. If it had happened INSIDE the chamber, as you suggest, the case would not be splayed apart as it is. The chamber would have contained the rupture and the split would be more uniform....and the case would not be bulged all the way around as it is.

Yes it obviously fired out of battery but I would say the main cause was the bullet setback on a stepped case. It might not of blown out of it wasn’t a stepped case. Don’t know what press the ammo was reloaded on but my 1050 gets stuck on stepped brass and won’t resize cases. Wonder if press could have had similar issue on sizing/depriming and didn’t fully resize and that’s possibly why round wouldn’t chamber all the way if you don’t case gauge ammo. 

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The issue is not the ammo.

My main concerns are:
1) is the bullet denting somewhat normal, or are there chamber and or feed ramp issues?
2) It seems like if the case gets damaged during feeding to where it wont fully feed, it is guaranteed to be lit off OOB. This one happened while my son was shooting, and it stung his face and hand. I'm not real happy about that.

I think I need to contact PSA. The inherent ability of an AR9 to drop the hammer out of battery means that it MUST feed ammo without damaging it.

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I will certainly agree in contacting PSA and at the same time, recommend trying different ammo and find out if it’ll make the same marks like the ones you had on your reloads.

 

Do you have any factory ammo to try out?

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11 hours ago, Sarge said:

Try a few different magazines and see what happens.

Magazines were my next question on this. These rifles come with an ETS mag normally. OP, have you tried a Glock factory mag yet?  If it is making those marks with different bullet styles something seems off with the way it is feeding. My PSA barrel was not ramped, so that makes you rely on the feed angle of the mags. For those saying the PSA chamber is short, they changed the chamber a while back, and they are much more generous now. I was able to seat 147s out over 1.140. The new barrels are marked PCC if they have the longer chamber. 

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