FN 509

The FN 509 is a polymer frame striker-fired semi-automatic pistol manufactured in Columbia, South Carolina, by FN America, a division of FN Herstal. It is chambered in 9×19mm Parabellum featuring double-action operation and a Picatinny rail located forward of the trigger guard. Tactical, midsize, and compact variants have also been made available.
Background.
As part of the XM17 Modular Handgun System competition (MHS) initiated in September 2015, FN Herstal entered a polymer-framed, striker-fired pistol, apparently based on the FN FNS. After SIG Sauer won the competition in January 2017 with a modified version of the P320, FN America brought a version of their entry, now known as the FN 509, to the commercial market. FN sought consultation from retired SFOD-D operator Larry Vickers during early development of the FN 509. FN America stated that during development and testing of the MHS entry and the FN 509, over a million rounds of ammunition were used.
Features.
The FN 509 is a striker-fired handgun with a stainless steel slide with ferritic nitrocarburizing finish and a polymer frame. Black and flat dark earth (FDE) colorings are available. Barrel length is . The slide has serrations on both front and back, for easy slide manipulation. There is a full-sized grip, housing 17-round magazines; 10-round magazines are available for states with a high-capacity magazine ban. The backstrap of the grip accepts interchangeable inserts; one arched and one flat.
Variants.
Several variants of the FN 509 have been made available:
Also available are an inert training pistol, and a Simunition (simulated ammunition) pistol.
The subcompact FN 503, introduced in March 2020, uses the "design, performance and reliability standards" of the FN 509.
Specifications.
For all variants, 10-round magazines are available for states that restrict capacity.
<br>
 For the Tactical variant, 24-round extended magazines also available.
<br>
 For the Compact MRD variant, 15-round extended magazines also available, which increase height to .