Here is the patient with the problem, this is a 45 Colt Carbine barrel, the scope base holes are drilled with the base at an angle.
This is the setup I use to check how level the scope base is and to drill new holes in the shotgun stubs I use. Kitchen counter top with a back splash.
The barrel as sent from the factory has a canted scope rail, I use a piece of cleaning rod to lay across the scope rail and sight against the back splash of the counter.
Properly aligned and level looks like this.
With the scope base screws removed, slide the scope base forward a little more than one screw diameter to get some new metal to drill new holes in. Attempting to plug the old holes and drill part way into the old hole will probably fail and result in a mess. With the scope base level and aligned, and without touching the base or barrel, put one drop of super glue into the front and rear hole, wait 10 minutes.
Now out to the drill press and mark the holes, I use a drill that will just clear the hole in the base with no slop, this puts a mark exactly in the center of the scope base hole, it is about a .140 inch drill bit.
Now just give the rail a sharp tap with something and shear if off the barrel. Using a tap size drill for the scope base screw (.120) I think, drill the holes with the press. Remember to set the depth stop so as not to drill into the chamber which would be an undesireable event.
Now the taps. From top to bottom a standard tap, a plug tap and a bottom tap. The standard taps are kind of worthless in shallow holes, so start the threads with the plug tap and then move to the bottom tap.
One thing I forgot to mention, before you drill the new holes, and for sure before you tap the new holes, put filler screws into the old holes. This supports the thin wall between the old and new holes and keeps you from breaking through it with the drill or tap. (Don't ask how I learned this)
Now just clean it up and mount the scope rail in the new holes. Good luck, yours results may vary.
Larry
