P-07 KaBoom

[deadduck357]

Ouch! A P-07 had a nasty Kaboom, posted on TFB. http://www.thefirearmblog.com/blog/2016/12/28/cz-p07-ultra-kaboom/

[Tok36]

Well you do not see that everyday. There is a good discussion in the comments of the article debating the cause of the kaboom if anyone is interested. A double charge in factory ammo seamed to be the most popular cause that was discussed. 

Interesting stuff, thank you for the link.

[Winkel]

There were several 'out of battery' comments too but like one poster said, I would expect that even being slightly out of battery, the hammer wouldn't be able to sufficiently contact the firing pin.

If anyone sees a follow up to this, please let us know.

[hokiefyd]

We're fortunate to have the brass case to observe in this case.  It sure does look like the round was not fully seated in the chamber.  There's a distinct demarcation between "expanded" and "normal diameter" on that case -- if it were fully seated, I doubt the case would have been allowed to expand like that.

I remember seeing a YouTube video describing a situation where someone let the slide forward on a chambered round and the firing pin was protruding from the slide face and it caused an unintended discharge.  I think a physical malfunction of the gun was determined to be the cause, but I think that was a particular pistol where that was known to be a possibility -- it could even have been recalled, I don't remember.  Does anyone recall seeing that video?  For some reason, I'm thinking it was a Real Guys Reviews video, but I can't seem to find it.

I wouldn't think that could happen with a modern pistol with a firing pin block.  But, as the blog author has stated -- it seems like it's got to be a REALLY improbable cause in this situation.

[deadduck357]

Yeah would also like to know what results were found that led to the kaboom. Hopefully nothing to do with "frame bulge".

[LonChaney]

Doesn't look like an out of battery detonation. Been there, done that. Here's mine:

[SI VIS PACEM PARRABELLUM]

Yeah would also like to know what results were found that led to the kaboom. Hopefully nothing to do with "frame bulge".

Most likely an overcharged case or bullet set back but nothing to do with any frame bulge. That was an issue with the early P-07 DUTY models that has long been remedied and even those guns that had the infamous bulge never blew up. This kind of failure can damage any gun anytime. This is absolutely ammo related.

[armoredman]

Good point.

[M1A4ME]

The base of the cartridge has to be in contact with the face of the bolt/slide as it moves upward from the magazine to enter the chamber.  After all, the rim slides under the extractor doesn't it?  I know (from dropping a round in the chamber and then letting the slide go forward on my P07/P09 guns that the extractor cuts a big chunk of brass out of the rim if the extractor is forced over the rim vs. the rim sliding under the extractor as the rim moves upward.

If the cartridge base is sliding up the face of the slide/bolt wouldn't the firing pin, if it was stuck forward and protruding from the firing pin hole, put a mark/knick in the rim as the rim struck it during the upward movement?  Would the force of the cartridge base/rim striking the firing pin knock the firing pin back into the slide?  Or just hang up the slide to stop forward movement?

If the case was overloaded (I'm not arguing that it was/wasn't) and if was fired normally by the firing pin after the slide was fully forward the case fully chambered, what's the change that the slide might start rearward while there was still enough pressure present to blow the case out?  Would anything, any amount of pressure, speed up unlocking of the barrel and slide rearward movement while there was still that much pressure in the barrel/chamber/case?  Doesn't seem likely.  That bullet would be moving quite a bit faster than normal anyway.

While the case is bulged, it appears the case blew out very close to the rim, not up above the bottom of the sidewall edge/corner.

I measured my recovered 9MM brass from my CZ 85/FC case blow out a few weeks ago.  I had 6 FC cases and 1 RP case.

#  Maker  OCL               inside case depth from mouth to base    difference
1    FC     0.7385           0.5675                                                 0.1710
2    FC     0.7440           0.5725                                                 0.1715
3    FC     0.7410           0.5725                                                 0.1685
4    RP     0.7440           0.5735                                                 0.1705
5    FC     0.7410           0.5735                                                 0.1675
6    FC     0.7460           0.5840                                                 0.1620

The difference puts the inside bottom of the case a visible (but not sure how to accurately measure it) distance above the bottom of the sidewall of the case.

When mine blew out, the sidewall separated from the base.  I have no idea if that reduced the amount pressure on the inside of the gun slide/frame (because it blew out 360 degrees around the case) vs. the one in this thread (blew out only a small portion of the case and therefore concentrated the pressure in that small part of the slide/frame.)

[eyetat]

I would be interested to see if there was a squib I have seen it with factory ammo at a IDPA match.

[armoredman]

Reply from CZ-USa about this incident;

Classic example of bad case webbing. The P-07/P-09 have a fully supported chamber and the guns themselves are designed in such a way that there is no physical possibility of an out-of-battery detonation. The slide has to travel ?? before the gun is out of lockup, and the factory designers made it so that the hammer would strike the bottom edge of the slide instead of the rear of the firing pin once the gun comes out of battery.

[Earl Keese]

Reply from CZ-USa about this incident;

Classic example of bad case webbing. The P-07/P-09 have a fully supported chamber and the guns themselves are designed in such a way that there is no physical possibility of an out-of-battery detonation. The slide has to travel ?? before the gun is out of lockup, and the factory designers made it so that the hammer would strike the bottom edge of the slide instead of the rear of the firing pin once the gun comes out of battery.

I would think those guys that were pointing to an oob detonation aren't P-07/09 owners.

[Boriqua]

Reply from CZ-USa about this incident;

Classic example of bad case webbing. The P-07/P-09 have a fully supported chamber and the guns themselves are designed in such a way that there is no physical possibility of an out-of-battery detonation. The slide has to travel ?? before the gun is out of lockup, and the factory designers made it so that the hammer would strike the bottom edge of the slide instead of the rear of the firing pin once the gun comes out of battery.

Forgive my ignorance but what is
"bad case webbing"

[armoredman]

That's the area of the case that angles down from the case wall to the extractor groove, IIRC. I also posted this as an answer for the same thread at Guns and Ammo forum - you'd think I had sacrificed a small child on a black altar! Wow the hatred over there is intense...

[IDescribe]

I would think those guys that were pointing to an oob detonation aren't P-07/09 owners.

I get why people are thinking oob detonation.  If you look at this pick:



If you look at that pic, it looks like there was an expansion with the case sticking a quarter inch out of the chamber. 

HOWEVER, when you have an oob kaboom, it blows out into the least supported area, which is almost automatically the feed ramp.  This does not appear to have blown out into the feed ramp.   This looks like the safety feature that directs gas and force from an over-pressured rupture to the side and away from the shooter.  In this case, if it's bad webbing, it wasn't so much over-pressure as it was more pressure than the case web could handle.