Plate, thanks for the photos. Wasn't expecting the break line behind the collar!
For those interested, here's plate's thread which led to his contribution here:
Thread: replacement firing pin...
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Plate, thanks for the photos. Wasn't expecting the break line behind the collar!
For those interested, here's plate's thread which led to his contribution here:
Thread: replacement firing pin...
The long, unknown history of a damaged rifle must be taken into account. Looking at the stub of the broken bolt brings back the memory of personally seeing a soldier with a large stone hammering away, trying to get a jammed bolt open. I´ve seen No 4s used as sledge hammers and to lever the wheels of an Army truck. Any weapon that has seen active service is likely to have been badly mishandled in any number of ways. It says a lot for the Enfield that so many of them even survived.
I haven't seen a striker broken behind the collar either. But there's no reason why not I suppose depending on the tempering
It's not an Enfield part, but Snafu has a thread on the "M1 Garand/M14/M1A Rifles" forum that shows a pretty classic "fatigue" failure of a firing pin. No micophotographic techniques required to see the origin point, progression of the crack and the area where the final catastrophic failure occurred. No mystery there!
Link here: Firing pin failure last weekend
A new one popped up today on CGN, aparently happened using factory Belmont ammo. This one is a first for me ;)
https://www.milsurps.com/images/impo..._MG_1009-1.jpg
Based on the limited info provided by the poster, this is what I answered so far - though very difficult to diagnose from one picture over the internet... ;)
Quote:
I'd need to see images of the failed surface, but from the photo you posted, the failure looks more like an embrittlement fracture and not a shear failure. I think I see crystaline texture indicating the presence of martensite throughout the cross-section. This is not good for a part seeing impact stress.
I would tend to suspect the bolt rib on the handle-side was the bearing rib and the base of the rib where it meets the cylinder of the bolt body experienced a catastrophic fracture due to a non-rlieved stress point in the bolt from manufacture and subsequent hardening of the bolt.
Without more info, I'd chalk this one up to an unlucky hot round meets less than ideal wartime manufacturing practices with respect to heat treatment and the quench temperature being off before the bolt was reheated for stress relief.
The receiver looks to be a Savage, no idea what maker the bolt is, but the handle does look altered...? Has it been ground on or heated and bent? Perhaps subsequently water quenched? This could also embrittle the bolt to the point of failure during firing.
Interesting. I have the rear half of a bolt sent from a guy in Florida from a new No.4Mk.2, sn. A956 broken completely in half in the exact same place. It was a hot reload that caused the failure on this one. It blew my mind when he sent it. I'd never seen anything like it before.
The top of the bolt handle on the pictured bolt has been dished out to clear a scope at some time. I've seen them done like that before.
Immediate question that arose in my little pea brain is whether both locking lugs bore against the receiver body. Off axis loading to be sure, but that would take a boatload of action flex! Not a compressive failure, I don't think.
The rear half of the bolt I have is broken almost identically on both lugs with the break running forward. The one pictured looks pretty much identical except you can't see the other side for the body. The break is triangular looking from the top. I'll take a picture and send it to Badger tomorrow since I'm electronically challenged. As I said, t came from a newish, matching No.4Mk.2 that was being used in high power competition in Florida. You would think it doubtful that the bearings of the locking lugs was ill fitted or uneven. Of course ROF Fazakerley did have some quality control problems according to those in the know.
Even with a mismatched bolt, it would take a tremendous overload to shear the bolt body. Wonder what happened to the bolthead & cartridge case? Perhaps this was an overload on top of an obstructed bore?
The trouble with these cases is that the rifle and ammunition are never available for inspection subsequently...
Except for Brian Dick's example! Let's see what his photos look like...
A more detailed study of the entire action pictured above would be quite helpful. Hard to beat a hands-on examination, though, but, hopefully this thread will encourage study of such failures to at least make some sort of useful conclusions. Otherwise, the odd random photos will drive all sorts of rumors. It seems that most (90%+?) catastrophic failures of varios types of weapons I've seen "in the flesh" were caused by handloads. NO weapon is failure proof against some folk!