I've got one I'm using in a 223 carbine barrel. Got it from Cabelas. When it came it was rusty and half the rim was missing and I almost sent it back right away but figured I try it first so cleaned it up and went to the range.
Shoots standard 22lr ammo into about 2" or less at 50yd. about 3 or 4" low from the 223 ammo I'm shooting. If you run a search on 'em you can probably find more info.