Processing of Niobium-Lined M240 Machine Gun Barrels

: Niobium liners have been emplaced in M240 machine gun barrel blanks with the Gun Liner Emplacement with an Elastomeric Material process. The barrel blanks were hammer forged and machined to produce finished barrels. These barrels were test fired at the US Army Research Laboratory at a low rate. No liner movement or extension was observed during the tests, although there was a preexisting extension in the first barrel.