No. 5 MKI Bolts

[P-07ShortLee]

How many variations are there for the hole in the No.5 MKI bolt handles?

I see mention of a more 'standard' hole used for BSA & Fazakerly production from 1946-1947, and of "early" bolts having a larger hole and, finally some reworked (in the 1960's?) that have had the holes enlarged.

What is the size of the "early" hole, and when were the reworked holes done?

Information

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[Peter Laidler]

I recall a discussion/class/lecture about production engineering in the small-arms industry by someone from BSA who used rifle bolts (among many other things I shouls add........) as an example of rifle production. Wartime manufacturers were at liberty to request a change in specification to enable them to make the best, most productive, economic and suited to the labour force use of what they had. The changes they suggested would be evaluated and then approved. One such change was to the bolt handle where some manufacturers wanted to delete the hole in the handle and the groove in the long locking lug (the one on top.....). The omission of the hole was approved for all manufacturers BUT some manufacturers used this hole as a fixture and for them to eliminate it from production was a major blow, meaning that many fixture jigs would have to be changed. So those that needed the hole were left to leave it as it was. Those that didn't, could eliminate it.

That's why both were used throughout production. As for the slot in the bolt, this was rejected because it was an immediate identifying feature of a No4 bolt that would avoid a No1 and 4 bolt being mixed up. I think one will fit the other but not the other way round. One Major Shepherd at Enfield was involved in this. Sound familiar........? Yep, that's him, the S of Sten gun fame

There was another lecture at Shrivenham by a Mr Mitchell from the Austin Morris MG body pressing works at Swindon (later the engineering director of MG) who discussed a similar thing relating to body panel production. Just a simple style change, where a badge or fitting might have to be changed on a body panel wouild cost thousands of thousands of ££'s. That's the reason why the MGB Mk2 with the recessed grille retained the little hump in the front of the bonnet. The production engineers and MG said that it was '....to give the big long compound curvature of the bonnet more rigidity at the front'. Not at all.............. It was to save thousands of ££'s in tooling costs. To change, just to delete the tooling for the multi holed MGB MG GT on the tailgate to a 3 hole simplified MGB badge was another financial money pit

Oh, where was I......... I seem to have gone off the subject. But back to bolts.......... While we were FTR'ing hundreds and hundreds of them, if it needed a new/replacement/good-reused bolt, it just got what was next. Blued, stoned, fitted and that was it! I think that eventually all of the part numbers were pooled, codified and you got whatever the blanket stackers at the Ordnance depots sent over!

[Roger Payne]

Somebody will no doubt jump on me if I'm wrong but I think the bolt handle knob on an original No5 bolt has a larger hole in it than the standard hole in a No4 bolt. However, many of the No5's I've had over the years have been re-bolted, so in that case, as Peter suggests, anything that's serviceable goes.

[P-07ShortLee]

Peter, do you think the bolts that had the holes enlarged during rebuild were just done to bring all the holes to the same size/add holes on bolts that were not made with them? Or had it something to do with weight savings? As I understand from what you're saying the holes were originally used to aid in the manufacture and started during No4 production so I guess weight wouldn't be a reason to enlarge the holes post manufacture.

Roger, I think BSA made No5 bolts had the smaller of the factory knob holes with Fazakerly being a larger diameter. Then the No4 bolts thrown into the mix and it gets confusing, a post I found mentioned early No5 bolts (1944?) with a larger diameter hole than the rest of No5 production from 1945-1947.

And I think it has been said that some bolts had the hole enlarged during rebuild, but apparently not during FTR since they would have either reused the original bolt or spares until exhausted. I haven't seen a mention of when these bolts were modified but it must have been after production had ended? Unfortunately the post that mentioned the early bolts didn't mention the size of the hole.

[Roger Payne]

Thanks for the advice. However, it does surprise me that any bolts had their holes enlarged...........I wouldn't have thought it would have been worth the bother. Do you know from where the thread you mention originated?

[Peter Laidler]

I can tell you with certainty that there was never ever an instruction to make the bolt hole larger! I'm not sure that the actual drilled hole was larger in diameter (although there will always be a few .001"'s in it of course) in some. It was the chamfer INTO the drilled hole that was greater.

But to us feet on the ground, with hundreds to get through, Armourers, a bolt was a bolt was a bolt..........

[5thBatt]

5/8" diameter for the early No5 & 5/16" for the later ones.

[Roger Payne]

Thanks.

ATB

[P-07ShortLee]

5/8" diameter for the early No5 & 5/16" for the later ones.

Thanks, do you know anything about those that underwent rebuild and had the hole enlarged?

It may have been reported on No5's that also had the "Ishy" bolt through the fore end.

[5thBatt]

Cant really help with that part but i have seen both size holes on No5s that have the ishapore screw & have been scrubbed & renumbered but without a letter prefix or a date to go by, its hard to know if they early or later rifles.