FN 509 Compact Tactical Vortex Viper 9mm Luger 4.32in FDE Pistol - 24+1 Rounds - Easily deployed as an everyday carry with the standard 12-round magazines or on the range with the extended 24-round magazine. The 4.3-inch cold hammer-forged threaded barrel makes it compatible with today's most popular aftermarket accessories like compensators or suppressors and the FN Low-Profile Optics-Mounting System. Browse all FN 509 pistol models available at Sportsman's Warehouse.