Merchandise Overview: IMR 4227 PowderManufacture of IMR powders dates back over 200 many years when the company was initially founded by E.I DuPont. Accessible for use in many reloading apps, the IMR number of powder is trustworthy by reloaders all around the world.IMR 4227 Powder in stock now could be the Magnum Pistol Powder from the IMR lineup.