One of my primary concerns at this stage is getting the breech face flat and square to the bore. I have and am pretty much going by "The Book" on making double flinters but he doesn't really go into this too much. He says, basically, to make 2 plugs and then file and fit them like you would on a single barrel. But in my mind it seems like if one had to get filed a tiny bit more than the other it would make the face of the apparent breech plug not match up. So here's my plan.
I'm going to turn a chamber sized guide out of steel and a part to fit over that with a smooth face 90deg to the bore and larger than the barrel width. I should be able to use sticky back paper and contact cement to put sandpaper on the tool face. I can then trim the barrels down and get them close with a file then use the facing tool to get both breech surfaces even and perpendicular to the bore.
I also think I can make a tool like this to taper/cone the first 1/2" or so of the chamber a couple of degrees to make the tap more likely to self center in the chamber as that's what messed up my 14ga barrels I was originally going to use for my first double build. Although, in hindsight, I think the 14ga chamber just may be a bit too small to run a 7/8 tap through and there was just too much meat to hold the tap in place once it got slightly off center.
I also have a plan for the plugs different than the one given in "The Book". Rather than make a plug that is close then file it to fit. I'm thinking I can make a casting of the chamber and then machine a plug based on actual measurements of the chamber. So it will fit (knock wood) without too much adjustment. It's rained too much to go hunting this weekend, so we'll see.
