Question #1:
Are SMLE and No. 4 firing pins and firing pin springs compatible between models?
Question #2:
Are major part groups of the SMLE compatible between the various nations of mfg?
Question #3:
Are major part groups of the No. 4 compatible by Mk between the various nations of mfgr?
Thx, Steve
1. Springs, yes, firing pins no.
2. Yes, generally.
3. Yes.
You can use a No1 firing pin in a No4 & vice versa but as the threads on the firing pins are different between a No1 & No4 you need to use a No1 cocking piece with a No1 pin & a No4 cocking piece with a No4 pin.
They are interchangable but only as a unit.