I'm going through a box of odds and ends I acquired at a gunsmiths retirement auction and found this large tap of very odd size and I'm wondering if anyone here might know what it is used on, it's in pretty good condition. It is stamped 3/4 1/32 10 lightning, thanks!

It is old

It is for tapping lightning plates and if you measure it you will find it to be .031 or 1/32 over nominal .750

10 is pitch TPI
3/4 is nominal size
1/32 denotes it to be oversize

thanks for the reply, not sure what a lightning plate even is though, but I'm always learning something new.

I routinely drill holes off location or too big

I call these "improvements" lighting holes