I chip in without direct expertise here, but would like to suggest that you consider a better make for the base of your work.

In automotive custom projects, it is said that 'the car you start out with is the car you end up with'. Double rifle shooting is a lot of fun, but the reason is partly the glamour of old makers, romantic history and great hunters' stories.

When you choose a Baikal you connect to a long history of five-year plans for tractorisation of collective farms, married to the sleek sporty handling of a T-54 tank.

You are going to put maybe $10,000 worth of your own machining time into this project. Give your work some respect, knock out 10 days worth of custom jobs for cash so you can buy an attractive name brand gun as your base. WIth that you would aim to be proud to carry your work and proud to pass it to the next owner.

Just my opinion! And yes, if someone offered me a nice Baikal I would not be too proud to own it, as is, but would not invest several times its value in custom work.