I had a Ruger M77 MKII in 30-06 that did the same thing yours is doing, only mine was moving the groups about 2" apart at 100 yards. Mine was floated and bedded, scope rings were lapped/aligned by gunsmith, and I end up putting 3 scopes on it, tried about 10 different kinds of ammo, and it just wouldn't shoot to my satisfaction. I end up trading it off after about a year of playing with it, decided I didn't trust it come deer season time. Mine would shoot the first group (2 shots) right where they needed to be, the next two would go high an right about 2" from aiming point, the third group would go low and left. It did shoot the groups nicely though!