Firearm accessories supplier Brownells says that it's experiencing "unprecedented" sales of magazines.Brownells has sold 3 1/2 years worth of PMAG magazines in just 72 hours, according to a statement posted from the company's official account on gun owner forum AR-15.com.It also says that it has sold "an even greater amount" of its own Brownells magazines.PMAGs, manufactured by Magpul, are used with AR-15/M4/M16 compatible weapons. "Its rugged design has made it as one of the top performers in the small-arms accessory arena, according to combat veterans who credit the PMAG with drastically improving the reliability of the M4," writes Matthew Cox at Military.com. The U.S....