George. Link should work now. I shoot lots of obsolete cartridges and have sources to make components for what I cannot find. Comparing this one to ones in 12.7x44 or 9.3x57R/360 also on the site, I would bet on a "guage" rifle barrel of 20 or 28 gauge. I already have a 20 gauge rifle and can find brass 28 gauge shells. Both are made to shoot a round ball.