No.1 Mk 3 Firing Pin threads

[Calif-Steve]

What would a No.1 Mk. 3 Firing Pin thread be? I have one that will not fit any of 5 Cocking Pieces. Hoping to carefully tap the Pieces, I hope.

[browningautorifle]

What would a No.1 Mk. 3 Firing Pin thread be?

Post number 16 in our threads below...read "Both SMLE and No4 are .250" diameter and have "fine" threads.
HOWEVER: SMLE thread is 1/4" x30 TPI "Enfield Special"; No4 is 1/4" x 26.

https://www.milsurps.com/showthread.php?t=53185

[Alan de Enfield]

What would a No.1 Mk. 3 Firing Pin thread be? I have one that will not fit any of 5 Cocking Pieces.

You probably have a No4 striker which is a BSF thread & which is a different size and profile to the Enfield/Whitworth form

As Jim says - a different tpi.

[Brian Dick]

I've got lots of nos SMLE strikers if in need.