I have two early 70s M-77s.
One in a .250 that is a sweet little gun that shoots an average of 1-1 1/2" after bedding & trigger adjustment. Very bullet particular gun, shoots less than 1" regularly but only with 87gn Sierra's.
One in a 7x57, that was like throwing a handfull of gravel at the target with every bullet except very long RN bullets which it would get in the 1-1/2" range. Bedding & trigger adjustment helped not a bit. Then I discovered the chamber was reamered so loose (as in mil spec) I'm surprised the bullet didn't come out the reciever end occasionally

Had the barrel cut back one thread & a 280 reamer run in it. It was an instant good shooter

Now average groups run about an 1"... it was better (lots of groups in 1/2-3/4 range) with a more powerful scope but it now has a 1.5x5 Burris & that's all I can do.
All in all I really like my early Rugers, smooth action & they just fit me

They could be better, would be nice to have detach mags.
The long action you can open the bolt with the saftey on, yet the short action you can't
