picked up one for the 10/22 at bass pro for 20 bucks. it will fit the ar as well. as far as not being able to use it. you have not shot one yet. if you use a reflex site, pull it tight to your shoulder with your weak hand, you can aim and crank. i dumped a mag into a old freon tank while walking towards it. it stayed on target and was easy to aim. it was fun, but for 20 bucks for the "trigger actuation device" and 8 bucks worth of ammo, well, it was fun....That same rig has been available for the 10\22 for a few decades now. And way back when 22 ammo was cheap it was a fun way to wear out a 10\22 barrel. As I recall it would fire 4 time per rotation. Probably close to the same mechanism and operation for ARs.