Naw, it'ud be fine. Rulebook sez:
RIFLE CALIBERS
· Must be centerfire of at least .32 caliber and not larger than .45 caliber.
· Must be in a caliber commonly available in revolvers. Examples include, but are not limited to, .32-20, .32 Magnum, .357 Magnum, .38 Special, .38-40, .44-40, .44 Special, .44 Magnum, and .45 Colt. The only allowed exceptions are the .25-20 and .56-50.