George, Looks Good. I'm always seeing potential safety issues..
That's a big beautiful wood stock you have there which 99/1OO times is going to support wahtever pressures you put on it. With 7 Screws in a row on the centerline, this makes for a potential weak point. It's an easy fix by putting in 1-2 Cross Dowels. Another thing I'd consider with the two bottom Screws of the Muzzle is to make those Machine screws which connect to a Bolt which has been dropped and buried into the top of the track. This will make the muzzle and gun stronger.
Nice Design. Thanks for Sharing.