IMR 4227 Powder For Sale IMR 4227 Powder is “the” magnum pistol powder in the IMR lineup. If it says magnum, IMR 4227 is the choice for true magnum velocities and performance. In rifle, this powder delivers excellent velocity and accuracy in such cartridges as the 22 Hornet and 221 Fireball. Grain shape is extruded (stick)
