The only powder I've used is 59 grs. R19 , Nosler 140, 150 partitions , and 160 AB. Rifles INC. Strata built in Cedar City UT. Only 55 fps spread between the 3 weights and they will all shoot a 3/4"group when I shoot all 3 at the same target @ 100 yds. I've killed a pickup load of animals out...