Just when you think you've heard it all....

[Son]

I came across a request for detailed drawings for the bolthead of a No4 MkI*. Ok, perhaps not anything unusual there, some collectors are always chasing tech docs of one sort or another.... But, this gent wants to make his own bolthead, and doesn't like the fact that the three boltheads he owns are different sizes. Now, the reason he gives for this is the fact he had a catastrophic failure of a bolthead which resulted in him getting sprayed with burnt powder residue, the shooter beside him being burnt also, and a passing range officer being struck by a piece of the shattered bolt head. Not wanting to allow the thread to deviate into an investigation of the failure, he has said only that he was shooting cast bullets out of handloaded ammunition at the time.... and could find no reason for the failure....

Anyone else hearing alarm bells here? I suggested he put his trust in the proven track record of the Lee Enfield action and parts, but re-visit what he had done wrong that could have caused the misshap...

I did say I wasn't aware of any such failure that couldn't be attributed to operator error in some way... have I made a wrong statement here?

Things that come to my mind from the scant information available so far...
Was it a DP rifle?
Was the bore fouled/ blocked?
Did his handload cause a serious overpressure by
1) a double charge of a fast burning pistol powder popular for lead pill shooters?
2) Or a half full case and a flashover of the powder.
3) Was the projectile sized correct?
4) Not crimped too tight or even too hard compound?

Another though just to mind, is the bolt missing the lug which prevents the cocking piece falling when the bolt isn't locked... allowing ignition and the unlocked bolt flying rearward from the pressure- effectively an out of breech ignition?

...any discussion welcome here... have I missed something? Or should we all be making our own boltheads so we aren't injured at the range?

Information

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[breakeyp]

I have been following this saga elsewhere and find it fascininating. The gentleman claims to be a machinist but does not want to reverse engineer the design by measuring parts he has in hand. He seems to think that the orignal drawings are a holy grail that will solve all his problems. He apparently does not know that the the drawing will be in Enfield Inch measurements where a US inch is not the same as the Enfield Inch. Not a problem for the British as Enfield made their own tools and gauges (which is why the problem existed into the late 1920's). He does not consider how the measured bolt heads can vary so much.

I wonder if this is all a mechanism to allow him to shift blame away from personal responsibility. Boo Boos and hand loaded ammunition go hand in hand.

[NavyShooter]

Had a similar incident here in Nova Scotia a few years back. I drove the RO to the hospital....remarkably quick service when they hear "Firearms malfunction"....

In the end, the determination was that it was likely a flashover of a reduced powder charge in the case due to inattention while reloading.

NS

[browningautorifle]

The thing you almost always find is you NEVER get all the facts about one of these incidents. It was NEVER his fault. There's always"By the way, one more thing" that doesn't seem to surface. This whole thing is undoubtably his error during reloading. Whether he's aware of it or not. If we had ALL the facts(powder, charge, primers used,squib possibility) we'd be able to point to exactly what the problem was before the catastrophic failure of a proven battle rifle. These guys are always a master reloader.

[Alan de Enfield]

Son - as you'll have seen I also asked him if it was a resurected DP rifle and what load he was using.
John Sukey asked the same Q's.

[Thunderbox]

I thought that guy's story was an exact repeat of one that appeared on that forum a year or so previously - and which appeared to be some sort of troll attempt? I predict that there will be no photos, no independent account, no clarification of the handloads in use....

[RJW NZ]

Hmm, out of all the things that could be deemed remotely feasible in the way of a firearms malfunction I would have thought a bolt head to be so well and squarely supported that disintegrating what is almost solid little lump of steel would be darn near impossible. I'm with son, I want to see pictures.

[muffett.2008]

C'mon you lot, this bloke has the right to commit suicide any way he likes, just a pity it will be another firearm related incident.

[Bruce_in_Oz]

Ah, reverse engineering; that's how we did the M-10 bolt and bolthead. The receiver and barrel drawings provided reference surfaces. The trick was to measure a LOT of components to establish a range. We then applied much of the tolerance schedule from the No1 Mk111 bolthead drawing to the No4 data and used that as a starting point before fooling around with the extractor and squeezing in a plunger ejector.

As long as the machine shop, the heat-treaters and the metrology lads do their part, it all works fine.

My two bob's worth is that there was something very odd about that rifle that blew up:

Excessive headspace from bolt and / or receiver wear / mismatch is a good place to start. Fitting a No3 bolthead MAY have closed the gap, but then there was still an ignition issue. So, maybe the rear of the bolthead was "adjusted" to allow greater striker protrusion. This only works up to a point (Boom! Tish!....Tish!....BOOM!!), because, eventually, the "reverse ogive" of the striker will jam solid in the matching bore of the bolthead. Now, were someone to "adjust" the striker or bolthead to allow more clearance, they could achieve greater protrusion: not that this is indeed a good thing.

Note also that the original boltheads were made from case-hardened mild steel. Early SMLE ones were malleable cast iron and later case-hardened mild steel. The term "nalleable" in relation to cast iron is important. What is also important to note is that the No1 Mk111 boltheads were only case-hardened on the face and the "hook" (the elegant bit that rides along the RHS rail). The rest was left "as forged". No4 boltheads were probably subject to similar treatment. The idea is that the "hard bits" will resist wear whilst the relatively "softer" bulk will absorb and transmit firing stress without catastrophic failure.

My experience with No4 cocking pieces has been instructive in that they seem to break much more often than No1 types. All the examples I have seen of fractured No4 types have been UK production. I suspect this is because Britain was actually being bombed whilst trying to produce war materials. Not only that but modern pyrometers and such were nowhere to be found. "Cherry red" is a bit subjective when you are working in different light colour balance and intensity on a 24 hour cycle.

ALL carbon steels "age". The classic sign is an increase in crystal size. Hardened ones tend to get harder and more brittle over a century or so. Ditto "hardened malleable iron" viz. older flint and percussion type toys. "Over-cooked" ones go bad a lot faster. It is interesting to note that Brit ordnance specs for the SMLE basically forbade the use of any "alloy" steels without the submission by the contractor of a quantity of specific sample pieces to be tested before use was approved. They also allowed for "re-heat-treatment" ONCE and only under closely specified conditions and only for certain parts.

[Lithy]

Hmmm........I've got a shot out 303/22 barrel and a couple of SMLE actions laying around.

I wonder how a .30 cast pill and a large dose of Trail Boss would go?

I'm backing the bolt head will remain intact