Strut and rut makes a valid point you may be overlooking. Let the gun cool down. Shoot the first round and check the target. Wait at least 2-3 minutes and try again. After 2 shots, you may have to wait 10-15 minutes or more to get the barrel to cool down again. Some guns like my old 30-06 are very sensitive to barrel heating. The first shot would be ok, then after 4 rounds under 5 minutes it would wander all over the target six to eight inches sometimes. If I let it cool down it would be ok. Try this before buying a vice.