Remington 7400 in .270 Win. Would not hold zero between range trips. Used it once for deer hunting, and was lucky enough to run across a brain dead white tail 2 point. Missed from a good rest at 80 yards. Missed again. Deer ran a ways. I followed. Shot and missed. Repeat several times. Finally the deer was so damned used to me shooting it stood looking at me from 30 yards away and I got'im.
Later took my son to the range and we both worked on getting it sighted. Put it in the case and went back with the gun and the son a few days later. Point of impact was a foot high and to the left about 8 inches. It got traded the next day
Sounds like you had a problem with your scope/mount and not the gun. I had a cheap scope on one of my rifles that had to be zeroed every range trip, I dumped it and spent a little more and no more zero problems.