That sounds like my old 30-06 i got rid of. I could go sight it in and not touch the gun then go shoot the next day and it would be off about 8 in at 100 yards. We never figured out what was wrong with it but i traded it in on a Tikka. I wasted about 100 rounds a month on that 30-06 over about a 2 year period. It had 4 different scopes on it and 6 different sets of mounts and bases and never shot good. It was sent to Remington multiple times and they said everything was fine. When it was sighted in for that day it would shoot under 1 in the rest of the day.