FN America 509 MRD — Mid-Size 9mm Pistol | 4" Barrel | Striker-Fired | Black Matte | Optics-Ready Slide with Holosun 407C Included | Non-Manual Safety | Optic-Height Sights | 10+1 Capacity | 2 Magazines | 66-101928 (66101928) | UPC: 845737018351
Meet the do-everything, carry-everywhere FN. The FN 509 MRD Mid-Size pairs FN’s battle-proven striker-fired reliability with an optics-ready slide and factory-mounted Holosun 407C red dot so you’re faster to the first shot and quicker on follow-ups. With a 4" cold hammer-forged barrel, non-manual safety system, and optic-height iron sights that co-witness with the dot, this 10-round package is built for concealed carry, duty-grade performance, and home defense—straight out of the box.
Why Choose the FN 509 MRD Mid-Size (with Holosun 407C)?
Dot-ready from Day One: No hunting for plates or guessing on height—your Holosun 407C is included and ready to mount/zero for rapid target acquisition and both-eyes-open shooting.
Carry-smart size: The mid-size frame and 4" barrel balance shootability, recoil control, and concealment.
Duty pedigree: The FN 509 family stems from rigorous LE/military trials—expect reliability, durability, and consistent trigger performance.
Non-manual safety simplicity: Internal safeties with a clean, consistent striker-fired press—no external lever to manipulate under stress.
True co-witness: Optic-height iron sights provide a daylight backup sighting system through the red dot window.
Key Features & Advantages
Caliber & Capacity: 9mm Luger, 10+1 rounds (two 10-rd magazines included) for compliance-friendly carry.
Barrel: 4" cold hammer-forged barrel for long service life and tight mechanical accuracy.
Slide & Finish: Matte black slide with front/rear cocking serrations for confident manipulations in rain, sweat, or gloves.
Optics-Ready MRD Slide: Factory footprint and mounting system pair with the included Holosun 407C (multi-coated glass, long battery life, shake-awake—model-dependent features).
Sights: Optic-height steel sights deliver lower-third co-witness for immediate transition if your dot is obscured.
Trigger & Controls: Crisp striker-fired trigger; ambidextrous slide stop and reversible mag release support left- or right-handed shooters.
Frame: Black polymer frame with interchangeable backstraps (where equipped) for customizable grip size; aggressive texturing for recoil control.
Non-Manual Safety: Internal striker block and drop safeties—no external thumb safety for streamlined operation.
Accessory Rail: Picatinny dust-cover rail for a white light or laser.
Note: Exact plate/adapter style, backstrap count, and Holosun 407C variant may vary by lot. Always confirm your unit’s contents on the box label and manual.
Performance You Can Feel
Faster first-shot sight picture: With the 407C installed and zeroed, simply present and dot—no rear/front alignment required.
Confidence in low light: Pair a weapon light on the rail with the red dot for faster identification and aiming in the dark.
Manageable recoil, faster splits: The 4" barrel and frame geometry help keep the muzzle flat for quicker follow-ups and tighter groups.
Glove-friendly controls: Serrations, large trigger guard, and ambi controls make manipulations straightforward in any season.
Ideal Use Cases
Concealed Carry (CCW): Mid-size footprint conceals easily with a quality holster, while optic-height sights maintain redundancy.
Home Defense: Mount a compact WML, keep both-eyes-open with the dot, and rely on FN’s proven reliability.
Range & Training: Learn red-dot pistol fundamentals, track the dot in recoil, and log consistent reps with the included two magazines.
Duty/Plainclothes: Serious, low-maintenance set-up with professional reliability and co-witness backup irons.
What’s in the Box
FN 509 MRD Mid-Size 9mm pistol, black
Holosun 407C red dot sight (battery included; model features vary)
Two (2) 10-round magazines
Optics mounting hardware/plate (model dependent)
Lock, manual, and factory case
Zeroing & Setup Tips
Mount & Torque: Install the 407C per Holosun/FN torque specs; use threadlocker where specified.
Co-Witness Check: Verify lower-third co-witness with optic-height irons; adjust dot elevation/windage as needed.
Confirm at Distance: Zero at 10–15 yards for defensive use (or your preferred distance), then verify at 25 yards.
Battery Discipline: Record the install date; replace the battery on a schedule even with shake-awake.
Holster Fit: Choose a 509 MRD + optic-compatible holster with clearance for optic-height sights and mounted WML (if used).
Specifications (Quick View)
Model: FN 509 MRD Mid-Size
SKU/Part #: 66-101928 (also listed as 66101928)
UPC: 845737018351
Action: Striker-fired, non-manual safety
Caliber: 9mm Luger
Barrel Length: 4"
Frame/Slide: Polymer frame, matte black slide
Sights: Optic-height iron sights, co-witness with included Holosun 407C
Capacity: 10+1 (two 10-rd magazines included)
Rail: Picatinny accessory rail
Controls: Ambi slide stop, reversible mag release
(Overall length, height, weight, trigger specs, and exact optic features may vary. Refer to the included manual for authoritative values.)
Compliance, Safety & Maintenance
Know your laws: Verify local/state regulations regarding optics, magazine capacity, and transport.
Routine maintenance: Keep the pistol clean and lightly lubricated; re-check optic screws after first 200 rounds.
Safe storage: Use a secure, locked storage solution; never store the firearm loaded where unauthorized access is possible.
Training: Regular dry fire and live fire with your chosen carry ammo to validate zero and reliability.
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The Bottom Line
The FN 509 MRD Mid-Size (66-101928) gives you a professional-grade, optics-ready 9mm with the Holosun 407C already in the box—no guessing, no parts hunt, just mount, zero, and train. With 10-round capacity, optic-height irons, and FN’s proven reliability, this is a modern defensive handgun that’s ready for serious work the day you bring it home.
The End
