The 12gr of Blue Dot load is probably not a hot load. I've shot 13.5 gr of Blue Dot with a 215 gr Valient SWC bullet and that load made 1125fps from my six inch model 57. The same bullet with 10.7 gr of Blue Dot made 950fps from my four inch 57.
Most times, I use 6.5 gr of Red Dot with the same bullet. That load makes 950fps from my model 58. Shoots very well. Dean