i'm jealous.. i'm still working on milkjugs at 150.
altho i suppose if i had something a little bit nicer than an old rossi .357, i might be able to go farther.
Factory rounds are highly variable. Hand loading is the only way to get reliability beyond 150 yards. Magnum is good, though. I like to load the 45 Colts real light so I can watch the lead bullet all the way to the backstop 400 yards downrange when I am shooting in daylight.