17 HMR. When I shoot with family members (four of us have them) we always bring them. I've had others shoot my Savage and they usually are competitive with everyone else within a couple 5-shot rounds, plinking at 100 yards at half-inch pasters, full soda cans, you name it. Little recoil, ammo cost not bad for an afternoon of shooting. A great and fun round for beginning shooters to develop confidence in their shooting abilities.