FN 66100780 509C Tactical 9mm Luger 4.32" Threaded 15+1,12+1,24+1 Flat Dark Earth Interchangeable Backstrap Grip. Full-size punch in a compact package with FN's patented Low-Pro le Optics Mounting System and unparalleled modularity of the FN 509 platform, the FN 509 Compact Tactical. The pistol is 9mm and striker-red with 4.32" barrel and the capability to accept all higher capacity FN 509 magazines. The patented FN Low-Pro le Optics Mounting System accepts nearly all commercial miniature red dot optics and features blackout iron sights that co-witness.