hugetacticles
I can not speak for anyone else but I have found that Rugers of all vintages need to be rebarreled. I have given up on Ruggers all together these days. I have seen them blow up, blow the barrels off, kill the nut behind the trigger, I have lost a few good hunting partners because of Rugger M-77's. as a general rule the Rugger barrels are crappy. you are better off rebarreling the rifle, then lightly bedding the rifle in the stock, then it should shoot sub 1". If you have a good Receiver then you have a good rifle, you just have one of the 94 out of 100 with a crappy barrel.
you can try recrowing the barrel, J&B Bore Paste to get the carbon out or the copper out, scrub the barrel to bare metal and then bore scope it, if it is rough then hand lapping will help if you are willing to spend the time. if it does not have big pits in the bore then shoot three rounds if they do not group then rebarrel it with something that will shoot well for you. or you can dump the Rugger and get something worth the investment.