FN 509 Tactical 9mm, BlackDescription The FN 509 Tactical, an extension of the FN 509 family, is based on FNs submission pistol that the U. S. Army tested for its Modular Handgun Trials, but includes the significant improvements to the design that were implemented in the FN 509. The pistol features the companys U. S Patent No. 10 352,654 Low Profile Optics Mounting System that enables the platform to accept more than ten commercially available miniature red dot (MRD) optics