Gallery of Dramas. Broken Enfield Parts!

[louthepou]

I haven't been posting for a while, life has kept me quite busy for the past year, but just for the record, I am salivating a lot while reading this thread. Thanks a bunch everyone

Lou

[jmoore]

nother photo surfaced:

href="https://www.milsurps.com/images/imported/2011/03/_MG_1019-1.jpg" target="_blank">https://www.milsurps.com/images/imported/2011/03/_MG_1019-1.jpg

I now think the faliure originated on the left side lug, which broke completely off, and then propagated to a stress point at the base of the safety lug. Uneven bearing could be the culprit, IF it was VERY bad and the load was hot.

That still doesn't make a lick of sense to me! It appears the LH lug fracture passes through the entire structure, either originating or terminating at it's outboard side, rather than it's root. There ought to be no load concentration there. IF it's the fracture terminus, then it's at least slightly conceivable. But then the question arises- From whence and when did the failure originate? Peter Laidler's comments seem worth investigating, if possible.


Brian Dick's example, on the other hand, is quite "textbook". Very nice! No fault of the design, just the operator/reloader.

[Thunderbox]

That still doesn't make a lick of sense to me! It appears the LH lug fracture passes through the entire structure, either originating or terminating at it's outboard side, rather than it's root. There ought to be no load concentration there. IF it's the fracture terminus, then it's at least slightly conceivable. But then the question arises- From whence and when did the failure originate? Peter Laidler's comments seem worth investigating, if possible.


Brian Dick's example, on the other hand, is quite "textbook". Very nice! No fault of the design, just the operator/reloader.

Looks like the fracture started at the base of the main lug/rib, which is quite a massive structure, then propagated down into the small lug. I expect that the steel crystalline structure is not uniform in an Enfield bolt, as the lug faces at least will have some form of work hardening in addition to whatever manufacturing treatment they received. Perhaps that why the fracture has left part of the lug face attached, and has gone through the middle of the lug instead?

Must have been a tremendous overload to achieve that effect....

[jmoore]

Hard to see much right now- will have a better lookie-loo later on. Will get the super high res. monitor fired up. Can barely access the forum during the week!

[jmoore]

OK! Having had a better look, Claven2's example (even if he just found the pic's I'll call it his -unless the real owner joins in) shares the protruding remnants of the LH lug like Brian Dick's. The photo made it appear as if the entire rear face of the lug was intact, which probably isn't the case. There IS some apparent action distortion. See the (pitifully) enhanced pics below.:


Photo #85a


85b



85c


85d


85e


85f


85g

Imagine the bolt lugs trying to move outwards from the bolt body. The hinge point is about where the fracture lines meet in Brian Dick's example. If the LH lug had a "window" in the action body it would probably shoot outward at considerable velocity.

I'm wondering if the rate of the applied load was different enough in these two examples to cause the differences in failure. A slightly slower pressure rise might have allowed the action body in Claven2's example to flex a bit more, creating the more asymetrical fractures. If only we had a lab, buckets of money, and some nice factory churning out multiple test victims (i.e. new rifles)!

[Peter Laidler]

That's an astute observation there JM, the actual body had spread and pulled away from the bridge charger guide and I expect the pin, retaining, pin axis backsight has sheared/partially sheared too.

I think that's the answer JM and others. Massive load down shaft of ill fitting bolt, slight twist, previous metallic fissure has weaken structure and snap. Simultaneously load spreads outwards and distorts body.

Yet another fantastic thread that's prompted a good classroom physics lesson

[Simon P]

An old article about barrel obstruction in a No4 from the 1980s


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[Claven2]

It's not my rifle guys! It's a random member over at CGN posting these photos. Some more got posted today:













I note that now the bolt is removed, the charger bridge insert looks normal again, so the action has likely elastically retaken its original shape.

The spent round doesn't look like Belmont to me, more like DI milsurp, boxer primed, and perhaps well overpressure. Factory over-charge? I have no idea.

[jmoore]

Boxer primed but the cup size looks like the British giagantor dimension. Enlarged a tad??? Aside from the cartridge case photo, which would benefit from calipers and a side view,too, the rifle photos aren't much help.

Quite the opposite, in fact! ALMOST, but not quite, any of the shots that would be useful. Frustrating.

It does appear the charger guide is still sprung slightly, though, see photo "#88b".

I guess the most interesting thing is that the action isn't visibly rooted. Not that it isn't in dire need of some NDT and possibly some "DT" to prevent further use!

ETA- If the action is fractured, I'd expect it most just behind the charger bridge, RH side. Next would be around the locking surfaces. Could be just stretched...

BTW, I noted that it's not your rifle, Claven2, but until you can give me another name, it's the easiest reference.

[Thunderbox]

I've got some fired DI43z in front of me - same case. The primer pocket in the photo looks much larger than standard, and the firing pin indent on the primer appears correspondingly smaller. Reloads?

I wonder if the shooter has checked the bore yet.... maybe two bullets jammed up there somewhere?