A weapon system designed by Eugene Stoner of M16 fame. The weapons were based around a single receiver, the "middle part" of the gun which received the bolt and ammunition feed. Stoner envisioned a weapon that was modular, which could be made into a carbine.. a light machine gun.. or an assault rifle.

Originally, the Stoner 62 weapon (designed in 1962, of course) was chambered for 7.62mm NATO rounds - which were used at that time commonly in the M14 rifle, but when the US Military decided to switch to the new 5.56mm cartridge and the M16 was adopted in 1963, the Stoner 63 weapon system firing that load was adopted. Stoner 62/63 weapon systems used the same firing mechanism as the AR-10 and AR-15 rifles that Eugene Stoner pioneered.

Only a few thousand of the weapons were manufactured from 1963 to 1971; the only actual combat it saw was with the Navy SEALs during the Vietnam war as a LMG (Light Machine Gun) Stoner 63 "Commando" with belt-feeding and box magazines which was the basis of the later FN Minimi (M249 SAW); Around 1970, the US Army Special Forces began testing the Stoner 63 as the XM207 weapon, but it did not receive as high a praise as from the SEALs, because the Army users did not treat it as well, with proper lubrication and cleaning. Production stopped with under 5,000 units sold in 1971.