My Grandson inherited an H&R 629 revolver. It is in excellent plus condition and has been shot very little. Hardly has even any holster wear. It is a four inch barrel with full size grips. We went out to shoot it yesterday and with 4 different brands of ammo the bullets were tumbling at the 7 yard range. Indeed they were showing an occasional full profile so it wasn't some odd tearing of the target. I checked for all the usual culprits which cause this but could find nothing at all amiss. It locks up tight, the crown is perfect, everything is nice and clean and functions freely.

I'm at a loss to explain this to him. Any ideas?