Any 5.56 x 45 bullet should get the job done. We have people posting pictures of whitetails taken with a 223 at 345 yard. The deer has a larger exit wound than a 7.62 x 54 with a 203 gr sp at 40 yards. A deer killed with a 223 had perfectly pink lungs blown out of it's body. I have shot deer with a 300 mag at less than 50 yards. The 300 mag didn't do half the damage to the deer.