Products Overview: IMR 4227 PowderProduction of IMR powders dates back in excess of 200 many years when the corporate was at first Started by E.I DuPont. Available for use in several reloading apps, the IMR number of powder is reliable by reloaders all across the globe.IMR 4227 Powder in inventory now may be the Magnum Pistol Powder in the IMR line