Atrius Development Forced Reset Selector (Mil-Spec Profile)

The Mil-Spec Atrius FRS is a single-side forced reset selector built for retro builders, M16A4 clones, and Colt-pattern rifles where the standard Atrius lever looks out of place. Mechanically it is identical to the original Atrius FRS: same heat-treated 4140 steel, same 90-degree throw, same three firing modes (Safe, Semi, Full-Semi). The only difference is the selector lever itself, which uses the traditional mil-spec profile with classic ridges and a pointer instead of the aggressive textured Atrius lever.

The lever shape matters more than it sounds. A retro A1, A2, or M16A4 clone with a tan furniture loadout looks wrong with the modern Atrius lever sticking out of the receiver. The mil-spec variant fixes that by mimicking the geometry of a standard AR-15 safety selector while delivering the same forced reset functionality underneath. It also gives clone builders running faux full-auto markings a period-correct lever to match the rest of the build.

Drop-in installation with mil-spec fire control groups (some minor fitment may be required), MPN ADG-FRS-S-MS, made in the USA. Atrius ships this in the same black bag as the standard single-side FRS, watch for counterfeit listings on third-party marketplaces. At $199 it matches the standard single-side on price and sits $50 below the ambidextrous version.