FRT
Forced Reset Trigger — a trigger that mechanically resets after each shot using the bolt's cycling motion.
Also: forced reset trigger
An FRT uses the cycling bolt to push the trigger forward against the shooter’s finger, mechanically resetting it for the next shot. Marketed as a fast-firing semi-auto trigger, FRTs have been the subject of repeated ATF reclassification and litigation — at various points classified as machine guns, then not, then again. Legality is unsettled and jurisdiction-dependent; check current ATF guidance and case law before purchasing.