No1MkIII* Extractor Thread Tap

[Hip's Ax]

Greetings, may I assume finding taps for a No1MkIII* is not possible? Just swapping the bolt head on one and the extractor screw will not go in, the new bolt head is unissued and I'd love to run a tap through that hole but the No1 threads are reportedly unique and the tap I am looking for is .126dia x 42tpi.

Thanks!

[JB White]

What are you changing the bolt head on? If you're mixing certain British or Australian parts with anything RFI (India) there might be your answer. It's not supposed to be that way but I have run into it on an inner band before. Got the parts mixed while cleaning and soaking the cosmoline off two rifles at the same time. No way they could possibly fit the corresponding screws.
I need to ask...why are you changing the bolthead? You do realize that contrary to US folklore there is no "just changing" when it comes to that? Many have done it but they haven't done it right and the problems are only masked, not repaired.

If you know for certain you are actually doing it right for the right reasons, you might drop a line to this site:

http://www.customscrewsandmore.com/

[Hip's Ax]

Thanks JB, this bolt head is 0.002" longer and while the headspace is acceptable (below 0.074") I would prefer to have that 2 thousandths tighter number. OK I was afraid of that, I wondered if the various countries might have wandered from the original intent of the designers. I'll put the old bolt head back on. Thanks!