Can't say about a Carbine or rifle barrel , But had a 12" Barrel that would shoot under an 1" all day long @ 100. Hornady 24ogr xtp's was it's fav. But cast 300gr WFNGC Did great also about 1 1/2" was the Norm. Have a 10" Contender barrel that will do the same with 240gr Speer SP's .