McLean, VA — May 20, 2025) FN America, LLC recently discovered a condition on the FN ReflexÒ MRD pistol that, in very limited circumstances when using the incorrect set of screws to mount specific optics, the pistol could experience binding, cycling issues, or interference with the firing pin safety block. The condition was first identified on a Reflex MRD with a Viridian RFX11 optic installed using the incorrect FN-provided screws labeled “604” which were too long. In this case, the screws labeled “603” should have been used.
When mounting any optic to the Reflex MRD, it is imperative to use the correct FN-supplied screw and only the correct FN-supplied screw. Do not use the screws provided by the optics manufacturer because those screws were not designed to interface specifically with the Reflex MRD and could cause damage to the slide.
The chart in the Reflex Owner’s Manual explains which size screw to use. It has been updated to include the Viridian RFX11 Optic. When installing the Viridian RFX11 optic, make sure to use only the FN-provided “603” screws to ensure proper function of the pistol (Top of Figure 1). Before installing all other optics, refer to the chart in the owner’s manual for the correct-sized screws. If your optic is not listed, please contact the FN Customer Service at 1-800-635-1321, or by email at [email protected].
Figure 1
Screw 603 on top. 604 on bottom.
To ensure that the correct FN-supplied screws are being used: while holding the optic separately from the pistol, place the screws through the screw holes in the optic and measure or count the threads protruding from the bottom; there should be no more than .045 inches, or 3 threads visible (Figure 2). The screws should also be installed to the correct torque (6 – 8 in/lbs), regardless of what may be recommended by the manufacturer of the optic. Take care not to overtighten beyond the correct torque settings as this may deform or compress the optic housing.
Figure 2
No more than 3 threads or .045 inches below the surface of the miniature red dot (MRD).
To view and read the FN Reflex Owner’s Manual or Optics Mounting Guide, please visit https://fnamerica.com/customer-support/owners-manuals/.
For questions about this service bulletin or assistance in returning an FN Reflex pistol for a repair or evaluation, contact FN Customer Service at 1-800-635-1321, or by email at [email protected]. Hours of operation are 8 a.m. to 5 p.m. Eastern time, Monday through Friday.
About FN
FN America, LLC—the U.S. subsidiary of Belgium-based FN Herstal, S.A.—provides U.S. military, law enforcement and commercial customers with a complete range of state-of-the-art, groundbreaking solutions developed around small-caliber firearms and associated ammunition under the FN brand name.
FN Herstal is the Defense & Security entity of the FN Browning Group that also includes a Hunting & Sports Shooting entity (Browning and Winchester Firearms* brand names) and operates globally.
FN product lines include portable firearms, less lethal systems, integrated weapon systems for air, land and sea applications, remote weapon stations, small-caliber ammunition, as well as modern and cutting-edge solutions to provide enhanced combat, logistics, maintenance and communication capabilities.
In addition to FN America—headquartered in McLean, VA, with manufacturing operations in Columbia, SC—FN Herstal is the parent company of FN UK in the UK and Noptel (optoelectronics) in Finland.
For more information on FN and its latest products, visit us at www.fnamerica.com or follow us on Facebook, X and Instagram.
*Winchester Firearms is a registered trademark owned by the Olin Corporation.
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