RIS / M-LOK / KeyMod

RIS (Rail Interface System) uses continuous Picatinny rail sections around the handguard, offering maximum compatibility but the most weight and the most snag points; M-LOK and KeyMod instead cut slots directly into the handguard body that accessories clamp into, adding a rail section only where one's actually needed.

M-LOK has become the more widely adopted of the two slotted systems in recent years, with KeyMod largely fading from new products, so most modern free-float handguards default to M-LOK slots with the option to bolt on a short Picatinny section wherever an optic, light or bipod requires one.

Mixing systems on one gun is common in practice — an M-LOK handguard with a short bolted-on Picatinny section for the optic — so the choice rarely means fully committing to one standard everywhere on a single build.