The standard load for the Mrs M70 in 257 Roberts has always been 120 gr Sierra HPBT behind 47.0 gr of R-22. That loaddoes just over 2800fps and is a killing machine. I also worked up a load using Nosler's 110gr Accubond with 40.0gr of IMR-4350 seated at 2.825" and it shoots well. I am quite pleased with using the slower powders in the Roberts.