OR

OR (Optic Ready) refers to firearms that are factory-prepared for mounting pistol red dot sights without requiring any further slide modifications. These typically feature a precisely machined cutout on the slide, a protective plate covering the cutout, and the option to install optics using adapter plates with the appropriate footprint for a given red dot sight. Airsoft replicas often copy the OR design – some GBB pistols feature interchangeable top slide sections or a built-in optic cut (e.g., the CZ P-10C GBB by ASG or the Glock 17 Gen5 MOS by Umarex).







The meaning of OR designation

The abbreviation OR = Optic Ready is a generic commercial label used by manufacturers to mark guns that are ready for installation of micro red dot sights (MRDS) or similar optics like RMR. It’s not a standard, but rather a mounting approach that may vary between brands. The goal is to allow users to directly install optics without slide milling.







Examples of firearm brands and OR models

  • CZUB: Models CZ P-10C OR, P-10F OR, CZ Shadow 2 OR
  • Sig Sauer: Models P320 RXP, M18/M17 etc.
  • Walther: Models PPQ Q4 OR, PDP OR
  • Heckler & Koch: Models VP9 Optics Ready
  • Smith & Wesson: Models M&P M2.0 OR
  • FN Herstal: Models FN 509 MRD (multi-mounting plate system)







Difference between OR and MOS

  • MOS (Modular Optic System) is a proprietary designation used exclusively by Glock for its optic-ready pistols. It refers to a specific mounting system with interchangeable plates.
  • OR is a general term for similar systems, but not tied to one brand.
  • Both solutions have a slide cutout covered by a plate and use adapter plates for mounting various types of red dot sights (RMR, Docter, Shield RMS, etc.).
  • Differences often lie in the mounting height, compatibility, and overall quality of the system.




Benefits of OR/MOS firearms

  • Easy optic installation without any slide modification.
  • Adaptability to multiple red dot footprints via adapter plates.
  • Precision manufacturing ensures proper sight alignment and durability.
  • Option to combine with backup iron sights (cowitness).

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