doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Model 12 burst

These are the remains of a 20g Model 12 burst, the center of which is about 6" from the muzzle. I have no information regarding the circumstances or load. My thanks to the contributor.



Muzzle to the right



Major Sir Gerald Burrard in the 2nd edition of The Modern Shotgun, Volume 3, The Gun and The Cartridge, �The Diagnosis of a Burst�, 1948
"By far the most common cause of burst is some obstruction in the bore, and so the first thing to do is to look for evidence of an obstructional (sic) burst, that is for a ring bulge. If a ring bulge is detected the cause of the burst becomes established beyond any shadow of doubt.�





The wall thicknesses just before AND just after the burst were .044". The thinnest part of the bulge was .038".

A segment of the barrel is at METL now for composition analysis and tensile strength testing. I might (later) have them section a piece from the burst edge for additional images, which should show ductal deformation and terminal cleavage, without low cycle fatigue striations. It might also be interesting to EDX any inclusions in the nickel steel.

It looks like pretty positive identifications of a ring bulge that bulged too far & exceeded the ultimate strength of the steel to me.

6" back from the muzzle- assuming a 28" barrel, doesn't compute, Drewbie== 6" back from the muzzle would place this disaster near the foreward magazine tube band-- Shame, too- a nice early Nickel Steel M12 20 gauge-- VSFU.. Foxie

The magazine tube barrel band thingie is 1" proximal to the beginning of the split; to the left of the 2nd image.

That, is too bad.

Best,
Ted

I sent Dr. Drew this barrel. My father took this barrel in at his gun shop probably 40-50 years ago. I have seen all types of obstructions and damaged barrels, some are salvageable but many aren�t. One can�t be too careful!

Yes, one can't- but that caution also applies equally to two, or WTH- even three- My grandfather always told me that. I never shoot reloads in my M12's at our club's tower pheasant shoots (note, I said "shoots" not "hunts"-- In the rush of the multiple flurries of "ditch parrots" getting airborne from the elevated tower- if you had a wad from a poor reload stuck mid-way uppa da tuba- and then followed it by firing a freshly chambered factory load- recipe for a disaster. RWTF

I'm trying to remember the rated strength of Winchester's Nickel Steel, wasn't it something incredible...like 110K psi or something near that (w/their Proof Steel at 130k)? If you have a barrel obstruction, it clearly doesn't matter what your tubes are made from, good damascus or fluid steel. That far down the tube from the muzzle makes it seem to me to be a wad, as Mr. Fox has surmised. The stamping of "Mod.1912" makes it a really early gun. They stopped that when...like in the early 1920s?

Here you go Lloyd
https://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=561800

and we'll know exactly what the tensile strength was of the nickel steel in this barrel in a few days

From my reading many years back, the term "elastic limit" really caught my attention and has stuck with me ever since that time. As I understand it, that is the point at which stress-induced deformation in a given material (in our case here -fluid steel or even the damascus family of steels) exceeds the material's ability to recover or rebound from that only split-second deformation impulse. Any bulge or even a full-scale burst caused by "hoop-stress" forces(?) which is a new term for me, is by definition an exceedence of a material's elastic limit. Am I stating or understanding this term correctly?