NO! A gun which is " safe to fire" (debatable!!) with say, three 50-grain Pyrodex pellets is NOT safe to fire with 150 grains of 777!! 777 is at LEAST 10% to 15% HOTTER than other propellants! Use at least 20 to 30 grains LESS of it than any other powder! IF you are using 150 grains of Pyrodex, I' d recommend starting with no more than 90 grains of 777 with the same bullets in tht gun!
Elde
777 pellets are actually closer to 5% less potent than Pyrodex pellets. You must be thinking of " loose" 777 which is approximently 15% more potent than Pyrodex RS/Select loose.