Texasbadger,
OK, Assuming the boltgun is is the one that is smoothbore rimfire, the 9.1x40R is ruled out.It is still proofed for a single projectile(ball/bullet), and it has rifle sights. There was 9mm rimfire ammo avaliable with shot and with ball.My uneducated guess is this gun is intended for 9mm Rimfire.If you can make a chamber cast and provide dimensions, this guess can be verified or refuted.Some versions of 9mm rimfire ammo is still avaliable,the version I have looks like a necked cartridge,perhaps it is intended for a 8.38mm bore.
Mike
