I used to have a Ruger... 77 MKII stainless... with a synthetic stock (in .243). I was never able to get good groups with it. Investigation of this pointed out two problems. The stock was rather poor quality (the forend was "warped")... and the trigger was heavy & rough. I believed, at the time, that, other than that, it was probably a good rifle. Alas, I didn't want to spend the money to sort out the problems. So, I sold the rifle to a good friend... with a full explanation of the problems. He replaced the stock... had the action bedded... and had a trigger job. Now, happily, this rifle shoots sub MOA, once he found ammo it likes (I have seen it do this). It is a different animal.
I, therefore, believe that Rugers are fine rifles....like many individual rifles (of all different brands).... this particular one just needed some sorting out. Unfortunately, every rifle is different -
there is the odd "lemon". In my experience, though, most rifles can be made to shoot well - if one takes the time (and effort) to make it so.