Pistol Speed Loader for .22 - .45 Caliber ACP Magazines MagLoader is a magazine loader for pistols from .22 through .45 ACP in both double and single stack magazines. MagLoader is a magazine speed loader made of nylon to last, and has no moving parts to break or wear. This pistol speed loader is compact, lightweight and easy to use. Simply slip your thumb into the size MagLoader that best fits you and press the top round down as you insert a new one.