Want to mount a Lyman 48 on a US Krag, gunsmith says receiver is just too hard to drill. Now I have seen innumerable Krags with 48s on them so there must have been a solution to this problem, hopefully without putting a torch to the receiver and softening the whole thing. Vaguely recollect reading about putting a drop of solder on the spot you want to drill and leaving the tip of the iron in it for a while. Any suggestions would be helpful.

You can spot anneal them with a battery and electrodes but I can't give you detailed instructions. You can also spot anneal them with a torch and a very fine tip. You can also drill them with a carbide bit available from Brownells without annealing. Tapping them afterwards is a dicey proposition but it can be done. I'm sure there are plenty of people here on the forum that can give you more/better ideas.
I think they are only case hardened and after you drill the hole with a carbide bit, tapping may not be too difficult but be sure to use a two flute tap, lots of cutting fluid, a sight/drill jig (like a Forster) and lots of patience.

Get one of the fellas that routinely post here to do it. Aint hard, just hard to do remotely

The usual method is to use a carbide bit to break through the skin, then a standard bit to drill the main hole, and finally the carbide bit again to break through the other side's skin. I use a 3-flute carbide bit sold by Brownell's and it works well.

Many times the hole will then need to be annealed to allow tapping the threads and this can be somewhat tricky. If heated too much, to a red heat, with the heat source removed abruptly, the steel of the hole will then be quenched and re-hardened by the cooling action of the surrounding unheated steel. The solution is to heat the inside of the hole so that the bright steel turns blue or purple, no hotter, and then remove the heat source slowly. The steel in and around the hole will then be soft enough to tap the threads.

An alternative spot annealing method prior to drilling the hole was detailed by Maynard Buehler in the first edition of Brownell's Gunsmith Kinks. He suggested heating a separate cube of steel to a red heat and then placing it in contact with the receiver at the hole's location, and allowing it to cool slowly. This would theoretically anneal the spot of the hole without changing anything else or discoloring the steel. I've never tried this method but apparently it works.

This is a common operation and shouldn't cause any problems for a knowledgable and competent smith.

Knowledgable and competent...
Regards, Joe

thanks all

This is how I was taught, and I did a few 03's and 03-A3's this way:
Heat a 1/4" diameter rod red hot and touch the rod and hold it to the receiver where the screw will be drilled/tapped. I never used a carbide bit or a carbide tap, just a good bit and decent tap.

quote:

Originally posted by vigillinus:
Want to mount a Lyman 48 on a US Krag, gunsmith says receiver is just too hard to drill. Now I have seen innumerable Krags with 48s on them so there must have been a solution to this problem, hopefully without putting a torch to the receiver and softening the whole thing. Vaguely recollect reading about putting a drop of solder on the spot you want to drill and leaving the tip of the iron in it for a while. Any suggestions would be helpful.

Once upon a time Redfield made a receiver sight that was unique to the Krag. It screw attached to the left side of the rifle with using 2 existing holes and extended screws. I know this because i got one really cheap at a gun show and walked around with it until I figured out what it fit. You might advertise for one of those sights.

To remove a Krag bolt you have to turn the extractor up on edge, which requires elevating the sight staff about half an inch. Problem with the Redfield is that staff cannot be lifted without winding the elevation knob all the way. Then you have to wind it back down again to the same point or you lose zero. The Lyman 48 removes with a pushbutton and goes back on to zero. Of course you can clean your Krag from the muzzle but that is not the best procedure.

quote:

Originally posted by vigillinus:
To remove a Krag bolt you have to turn the extractor up on edge, which requires elevating the sight staff about half an inch. Problem with the Redfield is that staff cannot be lifted without winding the elevation knob all the way. Then you have to wind it back down again to the same point or you lose zero. The Lyman 48 removes with a pushbutton and goes back on to zero. Of course you can clean your Krag from the muzzle but that is not the best procedure.

Old Redfields have the push button removal too.
I have one on a Lee-Enfield.

Only a few Redfields have this feature, and their spring retainers don't lock like the Lymans. Altogether a different proposition, IMO kinda like comparing a Chevy to a Lincoln.
Regards, Joe