During World War Two, a staggering number of non-firearm companies turned out guns. From Singer sewing machine to Rock-ola, to General Motors and beyond, machinery was retooled to supply arms to us and our allies.
Currently, things are being increasingly manufactured overseas by companies that had retooled at that time to supply guns to US forces. You ask, 'So what?' Well, that means that skill in manufacturing is being outsourced, and factories (with their related equipment) are now located in rather more unstable parts of the world. If a GM plant in Detroit can retool and crank out M3 Subguns, what precisely would stop one in Mexico from being retooled to produce AK rifles? And how certain are we that the Cartels cant get their hands on them?