I like my CZ 512 American, it's a good, solid 3/4" at 50 yards gun, with just about any ammo. It shoots better with the lighter weight bullets, but it ain't bad with 40s or 50s, either.
+1. I have the CZ512 Carbine in 22 WMR. It shoots all the Winchester and CCI ammo types well but, thus far, the A22 ammo has been the most accurate. I haven't tried any other manufacturer's ammo nor any bullet weight above 40 grains and don't plan on it.
