HA! Story of my life...comes in handy in many other circumstances. I settled on my keystone stock. The butt had to be sanded as I mentioned to fix some storage damage, removing its original factory stain.
So I practiced several different methods on a test piece...including Chuck's method of ball bit on a Dremel to free hand it. Here is what I settled on, which I think worked just perfect. I'm very pleased.
1. I marked the forward location of the bolt handle root from the top of the stock, then measured 5/8" to the rear. I used a sharp chisel to carve out a notch on top until I reached flush with the bolt notch on the receiver.
2. Next, I drew straight lines down from the sides of my notch, slight angle to the rear. I used the picture from
this post and
this one, and in particular the location of the rear stock bolt relative to the sides of the recess as a reference. I then measured 5/8" down from the top of my notch. These became my boundaries.
3. With sharp chisel, I notched the top of the area, going progressively deeper until the bolt started to close.
4. I used "jig", which was as simple as two blocks of wood, with the stock in between, in my vice, right side of the stock facing up. I leveled all 3 pieces in both directions. My router sat level on the blocks and, using a 5/8 ball bit lined up with the sides of my template, I plunged straight in until the all that was left of my notched area was the flats at 10 and 2 o'clock.
5. Test close the bolt, and continue to notch the top of the outboard side until the bolt closes all the way. this enrages the flat areas at 10 and 2.
6. back into the "jig", and plug into the router in until the flats at 10 and 2 appear perfect.
7. use the small ball bit on my Dremel to clean up all the rounded parts.
I'll add pictures shortly. Tonight I will finish sanding the stock and fit/sand the handgaurd. I did a bunch of test pieces with stains over the weekend. I've decided to stain with a 1:1 mix of birchwood Casey walnut, and rusty walnut and finish with raw linseed oil - might try usabaker's alkanet root trick in my linseed oil...
described in this post