My son shoots a Ruger M77VT (Heavy Barrel) 26" w/ 6.5X20 Simmons. 1/4" groups all day long. Destroys sage rats and rockchucks. Coyotes to 200 yards no problem. Best load is Win. brass, Fed 205 match primers, and 27.5 grains H335 followed closely by 28.0 grains W748.
I know several people who swear by Benchmark. We have not tried it.