Manufacture of IMR powders dates again about 200 yrs when the organization was at first founded by E.I DuPont. Accessible for use in several reloading applications, the IMR series of powder is trustworthy by reloaders all around the world.IMR 4227 Powder in inventory now would be the Magnum Pistol Powder in the IMR lineup. imr 4227 If it states Mag