Airsoft dictionary

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).

Airsoft dictionary