doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Blow Up Post-Mortem Part 2

I posted this question about a double drop of powder on Shotgun World in the Reloading Forum and this is the responses I received so far and I'm sure there will be more.

http://www.shotgunworld.com/bbs/viewtopic.php?f=13&t=392816&p=3123334#p3123334

I wonder if the slightly backed out primer indicates anything. Maybe pressure, over or not, rose quickly enough for the hull to hold on to the chamber wall without setting back against the face of the action. Maybe, since the primer doesn't appear near as distorted as the case head sounds, the pressure may have been falling when the headspace changed enough to let the primer back out.

I wonder if the shooter ever noticed proud primers on empties before. Does the other barrel show signs that some dimension change might be going on ahead of the chamber. Concentric rings showing, I wonder what might have been cleaned up that few inches into the barrel. Just interesting is all, thanks again Doc Drew.

Thank you David. I'll watch that thread.

Craig: I'll be checking the other empties today.

Off to volunteer at Under One Woof, a satellite Maricopa Co. Animal Control adoption shelter, then will start measuring all the edges.
MCAC is the second busiest animal control in the country; LA Co. is first. The kill rate is about 40% and some days 150 animals go through intake. When the economy crashed, 'migrant' families left in the middle of the night leaving their dogs INSIDE apts. and rental houses, or just turned them out. Some neighborhoods are running with Chihuahuas and Pit mixes (which BTW are the sweetest dogs in the shelter).
Just yesterday a guy was arrested for neglect of his horses
http://www.abc15.com/dpp/news/region_cen...aguila-property
Sherriff Joe has a very active and aggressive animal abuse unit and rehab facility. Dog and cock fighting remains a terrible problem out here.
http://www.mcso.org/Mash/AnimalCruelty.aspx
Sorry for the OT rant but child and animal abuse REALLY gets me going. Some live-in on meth beats his girlfriend's child to death at least once a month out here.

Anyway - talked again to the shooter, and his recollection is that all the previous rounds, and specifically the previous high 7 incomer shot with the left barrel, felt and sounded normal. He thinks the gun remained locked up after the blow out but will check with his squad mates as to who first picked up the gun.

This is Drew's first picture



I doubt there is a bulge in those barrels.

I interpret what I see as the tear started back by the powder charge and peeled forward toward the muzzle. The expansion evident toward the muzzled end of the tear is from the metal being bent back as the piece went forward. In Drew's picture that I posted above I do not see a bulge on the bottom of the barrel compared to the watertable.

The imprint of the extractor on the steel base, the lack of a bulge (in my opinion), and the primer sitting high indicate overpressure.

I have had some erratic results from my 9000 when some trash got caught up in the drop tube. The trash was most likely in an empty cartridge fired on a hunt and then dropped into my gamebag with the dead bird, the muddy dog boot that came off, and the miscellaneous twigs and leaves that fell in as I pushed through the brush.

Hard to assess what happened looking at small two dimensional images. The originals are 2MB and I'd be happy to send anyone the image if you would e-mail be at revdoc2@cox.net

This image looks a lot more like a bulge, starting at the lighter colored 1/2" forcing cone. Most of the lower barrel was blown away so we can't know if the bulge was annular

I know what Mike is looking at and tend to agree. However, both are probably right since the metal would have bulged before reaching its elastic limits and then bursting.

Trash in a hull: any hull that has been in a game vest or on the ground gets a thorough vacumning and inspection before reloading--always! Even clean, once fired hulls get a cursory examination at a minimum. I do not reload with any distractions--no tv and no people in the room. When there is any jam on my 9000 I remove all hulls, reset the charge bar, and begin fresh.

+1

Looking at the deformation of the solder line of top rib in this photo it sure looks like a bulge starting just ahead of the rib extension.

Bulge or distortion from bending, hinging outward, possibly the failure started at the breech end where there seems to have been less ductility. I wonder if the failure started ahead of the chamber why the breech doesn't seem to have peeled back a bit as it tried to hang on.

I tried loading a double charge of my standard skeet round on my MEC 9000 and it proved impossible. Here's the data:

Federal Game hull
17.5 grains Clays (35 grains in this example)
Downrange Federal SO clone
7/8 oz shot

Though the wad ram showed about 50 lbs pressure the wad did not collapse. You can see the wad and shot come up to the lip of the hull. Pre crimping was impossible. Had it been an ounce shot would have spilled everywhere.