Well, the US government could let out contracts with the civilian AR-15 makers (Palmetto, S&W, Ruger, etc.) for automatic versions of their civilian models, for way less than Colt, etc. make M4’s. Should be trivial to make them full auto.
That WILL tighten up the market for civilian AR’s. And, maybe, open up an international military market for the host of US makers.
Yes, it is. Just a bit more milling and a different fire control group.
The majority of the medium to large size AR manufacturers are already fulfilling international orders for select-fire ARs. Have been for years. Thousands of rifles per order.