I have a Marlin 795 (same gun, no heavy barrel though), and use a scope base by B-square. There are a few other bases that fit the stock rails, and they seem very solid. I am using a two-peice base and it seems to work great. The rings will not move at all. I think the problems people were having involved using cheap rings mounted directly onto the thin original rail. With a good base available for not a lot of money (~$40), I see no reason why this is even an issue, unless you are going to go completely cheap and use cheap $20 scope mounted on cheap $10 rings, in which case it may or may not work for you. I was originally going to go this route with my 795 as I thought it was a bit ridiculous to spend $160 on scope, rings, and base on a $120 rifle. Then I figured that I wanted to get as much accuracy and as little frustration out of it as possible, and decided to spend a little extra money and get what I want. I haven't had a chance to shoot it a whole lot yet, but to me, it is much better than a stock Ruger 10/22 I used to have which I thought was really heavy, had a awful trigger, and overall kind of bulky.
