Thanks folks! Daryl and I took it out to the range today, just to make sure everything was working. Ignition seems virtually instantaneous. We only fired about 10 shots and shot a tight group an inch low at ~ 25 yds. That's how I'm going to leave it...Quinn can file the sights in himself.
Ron, you are absolutely correct. The lid and hinge of the box is almost perfectly flat...and I won't do it again. I was thinking when I made the box that the original looked to me to be flat, and then I got my copy of "Lancaster Rifles" where nice colour pictures of RCA 79 shows that the box is indeed curved. Oh well - next time. In truth, I've never build a flat one before, so it's to be a one off.
Back to shooting, and one more comment. The rifle has a .50 cal. Rice bbl with a factory crown. The crown on this one is quite long and "steep" - not a 82 1/2 deg countersink - and I did not polish it. It loaded easily, was kind to the patches, and having put the sights in the very centre of the barrel, and equidistant above the bore, the rifle shot 6 o'clock and centred. Load was only 72 grains FFFg GOEX, .493" pure lead ball from a Lyman .495 mold, .020" tough denim patch and spit for lube.