Some semi-automatics may or may not function with sub-sonic ammo.. depends on the gun and the ammo! X22LRSUBA, if this is what it is is very good stuff. I've got a bunch of PMC Moderator... highly revered in the ranks of suppressor owners (at least back when it was avail.) as it is very quite, But I have a couple of semi-auto's that will not function with it!
Jerry
