Merchandise Overview: IMR 4227 PowderCreation of IMR powders dates back again above 200 years when the company was initially Started by E.I DuPont. Available for use in several reloading programs, the IMR number of powder is trustworthy by reloaders all around the world.IMR 4227 Powder in stock now is the Magnum Pistol Powder from the IMR lineup. I