The M203 is a single-shot 40 mm under-barrel grenade launcher designed to attach to a rifle. It uses the same rounds as the older stand-alone M79 break-action grenade launcher, which utilizes the High-Low Propulsion System to keep recoil forces low. Quite versatile, and compatible with many rifle models, the M203 was originally designed for the U.S. M16 and its variant, the M4 Carbine.
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