Creation of IMR powders dates again more than two hundred yrs when the corporate was originally Established by E.I DuPont. Accessible for use in many reloading apps, the IMR series of powder is reliable by reloaders all around the world.IMR 4227 Powder in stock now is the Magnum Pistol Powder during imr 4227 the IMR lineup. If it states Magnum, 422