The FAMAS was originally designed for iron sights only, as it predates the trend of issuing optics on standard infantry rifles (the marksman's rifle at the time of its development was the FR-F1). However, adaptations were made to mount optics, primarily the PGMP updated handguard, which locked more-or-less securely onto the barrel (the original handguard had no need to fit precisely) and had a proprietary mounting rail. While a variety of different optics saw field use (including EOTech and Aimpoint), the official issued scope was the Scrome J4.

The J4 is a pretty simple 4x scope, with 5 settings of reticle illumination. It was used on both he FAMAS and the Minimi, with a BDC reticle that is zeroed at 300m with chevron aiming points for 400, 500, and 600m. A small run of civilian sale examples was made; these have a mildot and crosshair reticle.

Doctrinally, the J4 was not so much a shooting aid, but a tool for observation, target identification, and fire coordination. It was issued to fire team leaders on the FAMAS. Today, these scopes are extremely rare in civilian hands (both in France and the US), as very few civilian examples were sold, and even fewer military ones got out into the collector's market.