Should be pretty easy to find a company - the designs are simple and low tech
What about Red Jacket ....... nevermind
The US Army tried to copy the German MG42 during WW2. Some draftsman made a mistake converting millimeters to inches, and allowing for the increased length of the US .30 cartridge, and the prototype didn’t work. Instead of correcting their mistake, they dropped the whole project.
Yet they jam far less than the M16s and can operate in an environment where there is a lot of sand.