Building a pistol is a sort of tricky business. All the patrs have to fit in a relatively small space. You're right to be thinking of barrel lug positioning, also ramrod pipes. How long to make the muzzle cap,how about squeezing a lock moulding into this tight picture. I might suggest looking at some reference books, and see how they look. Or put pencil and paper to work with your own design. As for the barrel lenght being 12", that is probably the limit, I would compare it to the 44" barrels on long rifles, and the 10' barrels to 42" barrels. I think they all look good if for-thought is applied, which you seem to be doing. I use to draw out my projects, but no longer do{ too lazy}. Now I just lay the parts on the stock and decide where they're gonna go. Also, you cut that out with a hack saw? Have you tried a hand saw? A 8 point cross cut I think would of been better. I have used a 6 point rip saw quite often, as long as you have control of them with a stiff wrist. Keep the faith with your project........George F.