I have been pondering a similar project. The barrel I am using is a blank that has not been turned to its final outside demension, or chambered. I bought a couple of stainless 1/4-28 bolts, and am working on a miniature version of a white lightning liner. Most .22's have a 14 twist, which isn't all that fast for a ball that small. I have also considered having a mold made to produce an elongated bullet for this rifle that if cast from a harder alloy might give good performance.
Hungry Horse
This is odd. I also have been tinkering with the idea of a .22 caliber muzzle loading pistol.
Lyman at one time made moulds for these bullets in various lengths and weights.
I have a section of a Marlin microgroove barrel and also have a 25 caliber finished ML pistol
barrel I made up in 1979 from a piece of a .257 Douglas barrel. It is breeched for percussion with a one
piece bolster breech and revolver nipple.It's octagon and muzzle turned for a guide starter.
When I was in high school,I made two 22 caliber ML rifles. One for a friend who is a retired airline pilot
and one for E.M.Farris. This was in 1954.I made a 4 cavity mould and used little paper patched bullets
in the first one and lubed Lyman bullets in the other one.
8 grains of 4fg will move those little bullets quickly.
Bob Roller