Your bedding may or may not need work. First thing I would do is get a trigger job. If your M77 is anything like mine was it is horrible. And forget that earlier post. Mine was a 3 position safety and my gunsmith did an excellent job on my trigger. That alone improved accuracy. And while it is at the shop, ask him to check the bedding. He may be able to do it all in one visit if a bedding job is needed.
I had both done to my M77 and group size was cut in half.