Is 50 grains of powder enough for what? Shots out to 150 yards ... NO. Make the gun fire and throw a powerbelt down range, probably. What is it you want to do with the 50 grains? Do you mean the two 50 grain pellets.. that should be a good load. I am not sure I would shoot 150 yards with a powerbelt at that distance unless I practiced a lot, and could place my shot. Also I would wait for the exact shot to present itself before shooting. Now with a Shockwave and 100 grains you might be all right.