I started down this path, but decided to go a slightly different direction.
I built my rifle around 25ACP.
An 18 inch barrel liner from Track The Wolf with a 1:14 twist, a few SS spacers, a piece of carbon fiber tubing, an Encore frame, and a little machine work.
I ended up with 16 5/8 inch barrel on that Encore frame.
For bullets I'm going to use .250 caliber PCP air rifle slugs. After powder coating it puts them at just over .251. The two weights I'm going to start with are 36 grains and 43.5 grains. QuickLoad estimates a max velocity of about 1400 fps for the 36 and 1200 for the 43.5.
I've only shot factory Winchester 50 grain ammo at the moment, but those are looking pretty good.
I'll post pics tomorrow when I'm at a computer.
