Bolt head sizes?

[Bruce_in_Oz]

As far as I know, the electo-pencilled markings are an Australian thing, often accompanied by two, roughly drawn crossed pennants. It is a proof mark.

It seems to be found on replacement bolt-heads, because the one in the rifle is essentially "proofed" with the rest of the barreled action at the factory.

I haven't found it, yet, but there is probably a clear set of instructions somewhere.

Interesting note on the Lithgow drawing for the bolt-head, C-643, dated 13January 1921, is as follows:

NOTE! For spares, qualify between 9deg and 13deg in advance of new component. Thus ALL replacement bolt-heads as first issued, have a built-in allowance for the gun-plumber to "fit " it to an already fitted bolt body and/or allow for thread-wear inside that bolt body.

The only marking specified on that 1921 drawing is the letter "M", which is to indicate bolt-heads made from "mild steel" as opposed to the originally specified "malleable cast iron".

Further digging required. I can't be the only keeper of old Lee Enfield tech docs on the planet.

Information

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[browningautorifle]

NOTE! For spares, qualify between 9deg and 13deg in advance of new component. Thus ALL replacement bolt-heads as first issued, have a built-in allowance for the gun-plumber to "fit " it to an already fitted bolt body and/or allow for thread-wear inside that bolt body.

I had a #5 that you had to fight the bolt to get the head to rotate enough to remove...suggesting it had never been fitted at all. It would be so tight that you needed a screwdriver to break it loose to lock it down when assembling. Now I get it...