10mm KaBoom have a good read

[The_Shadow]

Might be that some were not the best, but they did provide interesting info and learning experiences...so for all the ammo you have shared for us to get an indepth look...I thank You and many have also expressed thanks!

These were the bullets from the Dec 2013 over crimp issue that resulted in not chambering

[sqlbullet]

   I'm reaching over to knock on some wood but... I have shot everything everyone else has, typically more of it and some stuff others haven't. I have yet to blow up a gun    Have I been extremely lucky or got through a bad one then somehow?

No doubt the Witness is a lot stronger than than the Glock 20.  That doesn't mean that the Glock 20 isn't plenty strong for SAAMI spec, and beyond.  It just means when you hit ammo that is out of spec, it will let go in a Glock before a Witness.

[Condition 1-10mm]

Ok undersized bullet causes a set back which changes the burn rate of the powder. Since I'm not a balliectis expert I'm just adding my 2 cents here. Compressed powder load in a rifle makes the power burn slower and with the projectile undersized and excited the barrel and there was no barrel or slide damage I would say the brass did not reach proper PSI to seal the chamber and lock the barrel into place. I agree recoil springs aids in the locking time but doesn't hold the slide into battery the pressure of the cartridge does.( Cool how John M. Browning was able to figure that out over 100 years ago).So the barrel unlocked prematurely causing the extraction to start and then the full PSI was more than the brass could handle causing the brass to rupture sending the gasses down the mag well causing the frame to hold just enough to keep the shooter from losing a hand. Seems like the pistol worked liked it was designed to. I don't like Glocks but that does not take away from them being great firearms. To me it's Ford or Chevy thing. Not saying anyone is wrong but the physics and mechanics is what brought me to my conclusion.    I could be wrong but it is really early in the year for that. I tell my wife I'm human I get once a year to be wrong.

[Geeman]

Ok undersized bullet causes a set back which changes the burn rate of the powder. Since I'm not a balliectis expert I'm just adding my 2 cents here. Compressed powder load in a rifle makes the power burn slower and with the projectile undersized and excited the barrel and there was no barrel or slide damage I would say the brass did not reach proper PSI to seal the chamber and lock the barrel into place. I agree recoil springs aids in the locking time but doesn't hold the slide into battery the pressure of the cartridge does.( Cool how John M. Browning was able to figure that out over 100 years ago).So the barrel unlocked prematurely causing the extraction to start and then the full PSI was more than the brass could handle causing the brass to rupture sending the gasses down the mag well causing the frame to hold just enough to keep the shooter from losing a hand. Seems like the pistol worked liked it was designed to. I don't like Glocks but that does not take away from them being great firearms. To me it's Ford or Chevy thing. Not saying anyone is wrong but the physics and mechanics is what brought me to my conclusion.    I could be wrong but it is really early in the year for that. I tell my wife I'm human I get once a year to be wrong.

Here is what I believe happened with mine.  PPU brass too hard and sprung back after sizing.  Insufficient bullet tension allowed bullet setback during chambering.  The initial pressure (before a bullet begins moving) is a function of powder burn rate and the amount of room the gas can expand into, so less room means higher initial pressure.  Because it was a warm load to begin with, it resulted in a total case head separation.  By the shape of the ballooned brass, the glock remained locked during the event.

I'm not blaming the Glock.  I'm blaming Privi brass and the Midway claim that it was reloadable.  Any brass that won't hold its shape when resized is NOT reloadable brass!!!

Greg

[Condition 1-10mm]

 Brass will work harden that is why you see annealing on military brass. I have reloaded some PPU brass several times and I still have it in rotation 9mm, 223 I don't think I have any 10mm PPU.( I think I would have come up with a different name for my company besides Double PU). I really didn't read all the post I just watched the video and looked at the pictures and read what the shooter said since he was there. I have had a few case raptures nothing dramatic and that was from over used brass. I have never had a head separation. Since there was no barrel or slide damage I could see from the pics this was the only thing I think could have happened. Projectile excited the bore hit the target. We are talking micro seconds. Delayed blow back works because the case is stuck to the chamber wall because of pressure. When the pressure goes down from the projectile exiting the barrel the slide unlocks and extraction begins under normal shooting. It takes several 1000 psi to stretch the brass to seal the chamber. So I am saying the psi need to stretch the brass did not happen fast enough allowing the slide to unlock and the extraction to start. As the psi went up the brass that had been extracted could not with stand the pressure and failed. As we get have mistakes we learn from them hopefully never to repeat them. When things like this happen we are luckily to have them on video and the shooter documents everything as well as they can so we as shooters learn from these things. I am very glad nothing but a few scrapes and bruises happened to the shooter. Underwood is replacing the damages to his firearm along with his underwear. I hate this happened but there is a lot to gain from this and to be happy for.

[Geeman]

If you look in this thread a bit you will see the brass from my failed case.  It fits the chamber to a tee.  The location of the feed ramp matches the shearing of the brass in its seated position.  The brass was fully seated during the event.  If fact, the brass remained in the chamber while the case head was ejected.  The flattening on the left side could only have occurred if the pistol remained in a locked position.  My pistol did what it ws supposed to do.  I see nothing in the article that would lead me to believe anything different with his.

His failure was more more extreme than mine.  Mine cracked a frame, but it had to be twisted to see it.  It blew the magazine out, but was undamaged beyond that. 

Its been long enough my memory might be called into question, but I believe the PPU stuff was on its first reloading.  The brass was hard to begin with.  In my opinion its junk brass and there is a reason PPU is loaded as light as it is from the factory.  Tear down of the remaining loads happened easily with the kinetic bullet puller.

I can't comment on the current quality, but it will be purged from my reloading brass.  I back over it as I leave the range, then toss it into the spent brass bucket.  If you choose to reload it, do so with extreme caution.

Greg

[tommac919]

There was a thread on good brass and bad brass to reload... Glock talk if  IIRR

( found it... 18 pages; http://www.glocktalk.com/threads/can-we-create-a-stick-on-good-vs-bad-brass-to-reload.846395/ )

[The_Shadow]

Did you see This one? 

Company? (NNY)

BTW NNY is PPU in another language.

Prvi Partizan-Namenska Proizvodnja, Titovo, Uzice 31000, Yugoslavia. These are actually Cyrillic letters equal to "PPU in the Western alphabet.

PPU = Prvi Partizan, 31000 Titovo, Uzice, Yugoslavia

Headstamp codes can be found here http://cartridgecollectors.org/?page=headstampcodes