Item Overview: IMR 4227 PowderManufacture of IMR powders dates back again about 200 years when the corporate was originally Launched by E.I DuPont. Readily available for use in many reloading apps, the IMR series of powder is reliable by reloaders all across the globe.IMR 4227 Powder in stock now will be the Magnum Pistol Powder during the IMR line