G20 KaBoom update

[The_Shadow]

Yes, the letter PPU were at the six-o'clock, dropping down with the extractor holding/pulling it to the right as it blew out against the breech face.

[The_Shadow]

Look real close at the cartridge you show in this picture...


It appears to show some stress where the sizer finishes its stroke slightly in front of the extractor groove cut. 

[Geeman]

I would just like to say you guys scare the crap out of me 

   Can you take some measurements of the other brass (especially the PPU's) right above the extractor groove?

I'm a little rattled myself.

I measured maximum case bulge on the 36 other fired cases.  6 cases measured .432, and 30 cases measured .433.

All the PPU's measured .433" other than kaboom (total of 6 cases).   

Just above the extracto groove they measure .427" or .428" on the PPU's.

I repeat that Quikload shows this load at 4,000 psi under SAAMI max.  A warm load, but way less than many of your factory pulldown results.

I still say either premature lockup, or not locked to begin with and allowed to fire.  That bulge isn't a smile bulge.  The torn brass is where the feed ramp was.  The round was .124" out of battery before the pressure was released.

Greg

[Intercooler]

  For the 10mm I'm a true believer in having a hammer-fired setup. It always gets me thinking maybe that is why only one Company (that I know of) offers striker-fired.

[The_Shadow]

It very well could have been slightly out of battery, and not fully locked in...
As the brass is expanding, the tears starts to fold outward, it tends to pull itself further out of the chamber.

[Geeman]

It appears to show some stress where the sizer finishes its stroke slightly in front of the extractor groove cut. 

I'm using one of those defense flashlights for light on the pictures.  Its a reflection.

You can see the end of the die travel in the cases, even after they are fired.  You can also see the expansion of the cases here, but no smiles.




Greg

[The_Shadow]

Yes, smooth rounded expansion on those, the loaded round in the chamber shows something but it maybe a reflection of the barrel/chamber edge...

[Geeman]

It very well could have been slightly out of battery, and not fully locked in...
As the brass is expanding, the tears starts to fold outward, it tends to pull itself further out of the chamber.

I say the case head separation happened after the case ruptured at the feed ramp and after the case moved out of battery by about a tenth of an inch.  That's why the edges are shaped like a bulge rather than a bell.  The edges were attached to the case head.  When the tear happened, things came apart quickly as 5 digit pressures caused havoc in the ejection port. 

Just my theory.

Greg

[Yondering]

I disagree. Look at this pic; the case wall tore loose from the case head around the extractor groove. That's not a fault of the Glock barrel, that's just weak brass. That didn't happen after the case blew out at the feed ramp and released pressure.

Primers aren't a great indication of pressure, but yours don't show any pressure signs, including the failed case.

I think you just learned what happens with bad brass in the 10mm. I'd scrap that PPU stuff, if it was mine.

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[Geeman]

More Pics, this time with the blown case inserted in the barrel.







Now about Shadow being correct.  I was thinking the gun either didn't lock or unlocked early.  Shadow called it right about the case head failure.  The second pic shows a sharp edge the case expanded on to.  That edge is on the slide, and the barrel with the failed case inside goes into a locked up position perfectly.  The gun was locked during the expansion.

Greg

[Geeman]

I think you just learned what happens with bad brass in the 10mm. I'd scrap that PPU stuff, if it was mine.

I won't shoot another PPU case.  I just need to get the pistol back to functional condition.

Thanks,

Greg

[The_Shadow]

Its amazing how those PPU cases unzip from & unfold in the extractor cut...I don't know if PPU brass is better now than it was in the past.  It had a nasty reputation for awhile.

[MCQUADE]

That brass is suitable for framing!

[Geeman]

That brass is suitable for framing!

It certainly was suitable for de-framing (the glock frame)   

Greg

[sqlbullet]

Looks like they are making balloon style brass.