FN ® - The World's Most Battle-Proven Firearms.™

Thank you for your interest in FN Firearms.
Our site is for individuals 18 years of age or older.

Are you 18 years of age or older?



Available for law enforcement agencies only

The FN 509®  MRD-LE delivers more precision and versatility than any other duty-rated handgun. Building on the proven FN 509 lineup, the exclusive upgrades for law enforcement place every advantage in officers’ hands, with unmatched accuracy from a striker-fired handgun. Making up the new high-performance package is a conical striker, flat-faced duty-rated trigger and the FN Low-Profile Optics-Mounting System™ , for fast sight acquisition and consistent shot placement.

3-dot tritium sights co-witness with the MRD, for maximum sighting versatility and a clean sight picture, day or night. The industry’s most comprehensive and adaptable optics mounting platform, allows armorers to quickly mount common duty-rated optics.

The 509 MRD-LE is the choice for agencies who can’t settle for less than 100% reliability. With unmatched longevity in the most demanding trials, the FN 509 platform has been tested beyond 1-million rounds, chosen by departments for its compatibility with a wide variety of training and duty ammunition. With a polished feed ramp and chamber, consistent feeding and extraction exceeds every standard.

The smooth, drop-safe trigger compliments the perfect sight picture. FN’s precision trigger and high-performance striker, adapted from the FN 509 LS Edge™, has a positive wall before a clean break, improving accuracy for all officers. With a target-crowned, hammer forged barrel, a lifetime of tight groups is in reach.


FN Optics Mounting System Quick Setup & Reference Guide

66-101345FN 509F MRD NMS BLK/BLK NS 3X17 LE1845737015152


  • Caliber: 9mm
  • Operation: Double-action
  • Mag Capacity: 17 Rd.
  • Weight: 27 oz.
  • Barrel Length: 4.5"
  • Overall Length: 7.9"
  • Twist Rate: 1:10" RH
  • Height: 5.56"
  • Width: 1.35"
  • Trigger Pull: 4.5 lb. -6.0 lb.
  • Sight Radius: 6.3"

Primary Features

Patented FN Low-Profile Optics Mounting System fits most MRDs

Precision accuracy with unmatched sighting versatility

Duty-rated trigger breaks cleanly at 90°

Superior ergonomics for maximum speed and control


Quickly mount MRDs with the FN Low Profile Optics Mounting System™

3-dot tritium night sights co-witness to MRD, rear sight dovetail driftable

Front and rear cocking serrations for clean slide manipulations

External extractor, loaded chamber visual indicator


Drop-safe, duty-rated fire control group

Best-in-class flat-face trigger breaks cleanly at 90°

New, high-performance conical striker reduces trigger pull weight by ≈1-lbs.

4.5-lbs. to 6.0-lbs. trigger pull


4.5″ Target-crowned, hammer forged barrel for precision accuracy

Polished chamber and ramp for reliable feeding and extraction across ammunition types



Three interchangeable backstraps fit all hand sizes, improves sight recovery

Multi-surfaced texture for the perfect grip and faster follow up shots

Mil-Std 1913 rail fits all common weapon lights

Ambidextrous slide stop

Right-hand only magazine release

Black 17-rd magazines, high-vis low-friction follower



Three interchangeable backstraps

Three 17-round magazines

Four MRD mounting plates

Owner’s manual

Locking device

FN Ballistic case