Drilling & Tapping Mounts

[leo]

Is there some trick to drilling & tapping the receiver for scope mounts? I am putting a Redfield Jr base on an old Husqvarna rifle, I have the rear and centre screws drilled and tapped, but the area over the very front one over the barrel appears to be heat treated or tempered. 10 broken bits later and it barely made a dent in the receiver. Any body got any tips?
Thanks, Leo

[double gun]

Carbide and a mill

[leo]

That kind of equipment isn't in my shop😔. If there is no other route I'll have to send it to a smith to finish. Darn. I really wanted to do it myself. thanks for your reply.
LM

[bat119]

http://www.brownells.com/.aspx/lid=1...Project-Part-3

This explains how to do it

[Leeper]

There are a couple of ways to approach this. Before doing either, you should buy a good cobalt steel bit. This will handle material which HSS will not and is less fragile than carbide though not as hard.
The first method is to spot anneal the place where you have tried to drill. The surface, which was alrady hard, will have work hardened to an even greater extent. You can soften it by heating it with an oxy-acetylene flame. Heat until the spot you wish to drill is just past blue.
A second method is to grind through the hard surface with a diamond burr in a Dremel.
If you are not using an alignment jig, you may have some difficulty in getting the hole where you want it. If you at least have the action clamped in a drill press and start the hole with a carbide center drill, you will have a decent shot at getting it right. Otherwise, yours will be another of the myriad of Husqvarna actions with holes drilled in the wrong place. Leeper

[leo]

Originally Posted by Leeper

There are a couple of ways to approach this. Before doing either, you should buy a good cobalt steel bit. This will handle material which HSS will not and is less fragile than carbide though not as hard.
The first method is to spot anneal the place where you have tried to drill. The surface, which was alrady hard, will have work hardened to an even greater extent. You can soften it by heating it with an oxy-acetylene flame. Heat until the spot you wish to drill is just past blue.
A second method is to grind through the hard surface with a diamond burr in a Dremel.
If you are not using an alignment jig, you may have some difficulty in getting the hole where you want it. If you at least have the action clamped in a drill press and start the hole with a carbide center drill, you will have a decent shot at getting it right. Otherwise, yours will be another of the myriad of Husqvarna actions with holes drilled in the wrong place. Leeper

Thanks Leeper, I thought of heat to remove the hardened spot. You're on the button about crooked holes, some DIY gunsmith tapped and installed Weaver bases out of square with each other and offset to the bore, hence the reason for a 1 piece base. I plugged and lock tite the old holes and clamped the Jr base straight to the bore using 2 c clamps and 2 scope levels. So far so good.
LM

[leo]

Mission accomplished! A touch of heat and Cobalt drill bits. Next job. Overhaul the bolt so it clears the scope. If I don't screw it up I'll post pics once I'm done.