Drilling Caravelle Arms Brass Grip Frame for NM Blackhawk

[Hondo44]

That's a great idea use a proper counterbore and you could even grind the correct taper on it to save an extra step, and dedicate it to Ruger grip frame holes.

I'll admit, I use another shortcut to drill counterbored holes; I always drill a small pilot hole first for accuracy, then drill the counterbore with a regular tapered bit to ensure it's centered in the pilot hole. Then drill the clearance hole last.

 

[Aeroscout9]

In for pics when it's finished!

 

[Bruce757]

Here is how I would set up to drill those holes in the grip frame.
Strip all internal parts from the main frame.
Fit the grip frame to the rear and bottom of the main frame to a very close fit.
Mount the main frame in the drill press vice so that a tap size drill will easily pass through one of the holes in the main frame. This will require blocks and shims as the main frame has no parallel sides. Clamp the vise solidly to the drill press table and recheck that the drill slides down through the hole without side thrust of any kind.
Now temporarily super glue the grip frame to the main frame and let dry.
Install a center drill in the drill press and spot your hole.
Next install the tap size drill again and drill the hole.
A clearance drill then will open the hole for the screw.being careful not to cut into the main frame.
A counter bore from Brownells is the proper tool to countersink for the screw heads.
Heat from a heat gun or propane torch will break the super glue's bond far below any temperature that will affect the heat treating.

Repeat the above for the rest of the holes. After a couple holes are done the super glue is no longer needed,the screws will hold the grip frame.
Extremely accurate transfer of holes can be done in this manner.

More amazing information, thank you. Hopefully I'll be drilling by tomorrow and will be posting a finished photo. Hopefully. A buddy of mine is going to let me use his workshop and is also reading over these posts. Thanks, gents.