RE: 100 grains vs. 150 grains
i only use 80 grains pyrodex p and a 225 grain powerbelt and am only 4" low @ 150 yards. The bullet still packs a big punch for that distance and with only 80 grains.
Just remember that a 45-70 used a 405 grain bullet with only 70 grains blackpowder and would kill a Bison out to 200-300 yards.