The FN 509 is a mid-sized polymer 9mm semi-automatic pistol with a 3-dot sight and interchangeable backstraps so the grip can be fitted to the hand. It has an FN optics mounting system and a rail for accessories. This listing is a new pistol, and the photo shown is a stock image rather than the exact unit you will receive.

Its mid-sized frame and swappable backstraps let the grip fit a range of hand sizes. The optics mounting system suits a shooter who expects to add a red dot or light later. Because the listing describes the pistol as new, there is no used-condition detail to weigh, and the configuration is the main point to compare against other 9mm pistols. The grip size can be changed without buying a second frame.

Key features

• Mid-sized 9mm polymer semi-automatic pistol
• Interchangeable backstraps
• FN optics mounting system and rail
• 3-dot sight
• New, stock photo shown

Firearms ship to the licensed FFL dealer you name, where you complete Form 4473 and the background check.