I bought an Olympic Glock 9mm carbine. It is an M4 that fires 9mm from Glock 17 mags. This was perfect as my duty pistol is a G17. I run an Eotech on mine. I have reliably engages 15" gongs at 330 yards. Reliability went south at 350. I know of guys shooting these with real AR optics and hitting at 450. I can attest that hits at 330-350 sound like some hit that plate with a ball peen hammer!