This is a relatively slow burning propellant that is used in cartridges from 22 to 45 caliber. IMR 4350 is perhaps the single best choice for such popular applications as the 243 Winchester for all bullet weights, the 257 Roberts and the 7 x 57mm Mauser with most bullet weights, and the 30-06 with bullets of 180 grains or heavier. It has been the choice of at least one factory for the past loadings for the 243 Winchester, 270 Winchester, and the 300 H&H Magnum.
