US Army replacing the M2A2 ammo can in use since (approx) 1942
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with the new polymer based ammo cans called SixPAC ( name is based off of the 6.8m cartridge which this was designed to carry more effectively)
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While the benefits of this replacement are controversial one of the claimed benefit is :
manufacturing the polymer containers by injection moulding could broaden the supply base, with more than 800 potential suppliers identified in the US. Including field 3D printers
Source