No 4 Mk1* vs No 4 Mk II Cocking piece question

[rgallant]

I have built up a spare bolt for my rifle, it head spaces fine, but the screw I have for the cocking piece appears too large ?

The cocking piece is marked Mk II 67, the firing pin screws in no problem, but the striker screw will not, it is possible the screw is stripped the threads look kinda of iffy. But reversed the screw head will not seat into the cavity.

Before I go ordering another screw any suggestions ?

Oh spare bolt because the original is somewhere in one of 20 moving boxes with the original owner, because someone will ask.

Information

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[ssj]

Have you checked both lugs are taking the load evenly on the new bolt?

[Bruce_in_Oz]

Check that you actually have a keeper screw for a No4, because No1 (SMLE) ones look similar but have a different thread.

No1 keeper screws have a "flat" head with "coned" circumference.

No4 keeper screws, (at least the ones here), have a slightly domed head and a parallel circumference.

The threads are also radically different:

SMLE: -0.144" x 37TPI, "Enfield form"

No4:- 4BA (0.1417" x 38.5 TPI).

[rgallant]

Thanks for reply's, checked the lugs they look ok- used the stickies here to confirm. Will do it again before I go out just because I would rather be safe.

The screw appears right but after some clean up the threads are pretty much shot, so I will just order a couple more.

[Peter Laidler]

But did you check all of the many other points that make a bolt serviceable, such as lift, overturn etc etc............?

[rgallant]

Hello Peter, actually I went through all of your notes on fitting a new or replacement bolt and checking headspace etc, I have nice little binder now. It made for an interesting nights reading, then some head scratching converting what I read to what I saw. The overturn confused me the most until the light bulb went on.

I took it as a step by step process and when in doubt went back and re-checked - it has been an interesting learning experience, when the original bolt gets to me I can do the same for it.