VSG Airsoft gives his take on the S&T/Umarex HK UMP45 Sportline AEG in this video review. The S&T UMP sport line is an airsoft replica of the Heckler & Koch UMP, a .45 caliber submachine gun. It is manufactured under license by Umarex and features a metal gearbox, ABS body, folding stock, top rail, and railed hand guard for accessories. It also comes with a high capacity 420 round magazine.