A couple of folks here, and other places on the web have all had their best results with RL-7 and just a bit higher than your loading. It worked in several different Contenders for several different people and #3s but I would work up on it.

I had a barrel for 8-10 years that I had purchased for the scope that was on it.
Finally sold it was year to a guy in NC, he had it shooting 1.375 in a week at 200 with Sierras.