Finally done! Repro Longbranch No4 MkI* (T) First range day today!

Probably would be the best way. When I used the masonry bit to cut through the hard spot it had basically spot annealed it, that is why I was able to drill to the proper size and tap with the hss drill/tap afterward.
 
Actually I was told...some use spot annealing. It's a method to remove the hardening just in the one spot you're drilling. Personally I didn't like the sound of it.

http://www.cnczone.com/forums/general-metalwork-discussion/2826-drilling-hardended-steel-update.html

Probably getting the whole receiver annealed, drilling the holes and then getting it re-heat treated is the way to go.

Spot annealing works very well and doesn't have any effect on the strength of the receiver. You just need to have the proper tools to do it. Using a carbide bit is OK as long as your taps are actually hard enough to cut threads in the receiver.
 
I guess its been ten years since you built it, but Did you have to take quite a bit of material off the POF stock? I have one and its pretty thick in places.

Hope you track it down.
 
Back
Top Bottom