Accurate Powders is an American company that definitely lives up to its name. The complete line of smokeless powders for handguns, rifles, and shotguns is engineered and lab-tested to maximize the precision and performance. Accurate uses the best ballistic technicians and the highest quality components together to assure that every gun is better served with Accurate Powders Accurate 4100 is a double-base, slow burning spherical powder with exceptional metering characteristics. 4100 is an excellent choice for high performance, full power loads in magnum handgun cartridges. It is ideally suited for the 357 Mag, 41 Mag, 44 Mag, 454 Casull, 460 S&W and the 500 S&W.