doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com "The Southern" Chamber Burst

Raimey: here are pressures for 1 1/16 oz. loads reported by Major Sir Gerald Burrard, The Modern Shotgun, Volume II, �The Cartridge�, 1955 3rd Revised Edition pressures converted from Long Tons/ Sq. Inch at 1�
12g 2 1/2� 33 gr. Nobel Smokeless (3 Dr. Eq.) with 1 1/16 oz. - 7,885 psi
12g 2 1/2� 33 gr. C&H Smokeless Diamond (3 Dr. Eq.) with 1 1/16 oz. - 8,288 psi
12g 2 1/2� 31 gr. Smokeless Diamond (2.8 Dr. Eq.) with 1 1/16 oz. - 7,179 psi

Modern Kent/Gamebore English Field 12g
2 1/2� 1 oz. Traditional Paper @ 1295 fps - 6526 psi
2 1/2� 1 oz. Pure Gold @ 1295 fps - 7832 psi

Had a very productive meeting at METL this am with both a metallurgist (Andrea) and metallurgical engineer (Ryan). They were quite enthusiastic saying "This is ALOT more interesting that broken bolts!" and a bunch of the employees are "gun guys".
They also commented that the machinists had tears in their eyes chopping up the actions for composition analysis
I gave them the remains for mementos

These again are the questions:
1. Does the divot represent the failure initiation point, and is there evidence of porosity and/or a flaw there?
2. Is there evidence that the breech end barrel wall was over-heated in the original brazing?
3. Is there evidence that the braze joint failed, or that it was never properly brazed?
4. Is there evidence of low cycle fatigue?

re: #1 and #2 they agreed there was visual suggestion thereof, but were also quite clear in saying that they are frequently proved wrong by the microscopic examination.
re: #3 & #4 no way to tell without microscopic exam.

They agreed it would be much easier (cheaper) if we had the missing chunk, but we don't, so they will cut out the segment of barrel in question and do scanning electron microscopy to definitively answer those questions. They will provide full size images for posting here and on my website.

Did anyone check to see if the missing chunk is stuck in the tree it hit?

Heard from METL yesterday pm. The plan was to saw out the medial section of the barrel



BUT the machinist and metallurgist were concerned that the heat from the saw might distort the morphology of the fracture edge
I've asked them to not destroy the left barrel, which still might have some value as a replacement for another gun. The lifted rib could probably be harvested also.

Once again, it would be SO much easier with the missing chunk. I suspect tick & snake season has begun in N. Carolina and digging through the brush at Deep River would not be much fun.

METL will see what they can do, but it's obviously not worth the effort and (my) $s if a proper SEM can't be obtained.

Steel looks old and rotten to me...just saying.

Might try a saw that uses lubricant like most industrial horizontal band saws do. Just a little fluid drops the temp. dramatically.

Yes, that's the plan Steve.

Just heard from Ryan, and they believe they can get a good sample to evaluate the edge microstructure and braze. Unfortunately, the divot can't be cut out without cutting into the left barrel, but they agree that very likely IS the initiation point.

I�d be happy to walk around Deep River and look for it, if someone�s got a metal detector I can borrow and points me to the right station.

Thank you Bill. I sent a message to the shooter.

Perhaps you can elaborate on the exact process that causes steel to be "old and rotten". And if you don't think that we should be shooting old guns, then why are you here? Have a great day jOe.