I now find that I need to make a keyhole spanner to torque my front sight base on & off with...Using 5/8" aluminum plate, hole bored to ~.640" and a ~.290" slot...
(27) Hole was drilled to 1/2", slot milled, and hole bored out to ~5/8"+.
(28) Closeup of front sight base in keyhole spanner.
(29) Torquing the front sight base to the barrel with the keyhole spanner. Spirit levels used to align the two.
(30) Spanner removed; checking level again with level on top flat of front sight base.
Next up is facing off the muzzle and crowning.
(31) Muzzle face has been turned in lathe, slight chamfer cut on edge of muzzle, crown being cut.
(32) Barrel has been torqued on receiver/barrel extension; rear sight located, holes drilled for #4-40 screws, front sight base torqued on, hole drilled for #4-40 setscrew and being tapped in this pic.
(33) Angle plate has been mounted on mill table at 58º; barrel has been removed from receiver/barrel extension and leveled in barrel vise clamp; bolted perpendicular to table in preparation of milling extractor notch.
(34) Making first extractor cut with .093" Woodruff keyseat cutter.
(35) Second extractor cut with .200" Woodruff keyseat cutter.
(36) Cutting feed ramp with 10mm end mill. Barrel held in barrel vise clamps which are in turn held in angle vise set at 50º. My thanks to Gerry Tomek for his sleuth work in determining the correct angle!
(37) Just a closeup of the finished ramp cut.
(38) Torquing the receiver on the barrel again, to check extractor clearance in receiver/barrel extension.
I've received a donor frame, I'll be prepping that for a forearm lug soon. Couple other things need doing on the barrel, plus the rear sight leaf needs shortening. Always something.
Interlude
Off-topic, but worth relating...I was milling an aluminum block square earlier in the week, idly watching the end mill spin around in the spindle and the feed table move slowly along, keeping an occasional eye on the TV on the shelf above me, when the air compressor in the corner suddenly kicked in...It took about half a second for me to lunge forward and disengage the feed before the circuit breaker cut power to the 3in1 mill...The 3in1 has two 8.8A motors, one for the mill spindle and the other for the lathe/table feed...The compressor motor is 15A...All plugged into a 12/2 w/gnd wired circuit with a 20A breaker...
So today I ran 10/2 w/gnd to the 3in1 with a 30A breaker and moved the compressor to a 20A breaker. I usually know enough to run the compressor and build up a reserve and switch it off before running the 3in1, but this time I forgot. If the power cuts off while I'm cutting with the feed on, it can be disastrous to the workpiece and expensive to replace the broken cutter. Better to be safe now than sorry later.
Here's the finished breech - Extractor notch cut; feed ramp milled; barrel torqued in place.
