CMMG makes a short barrel that will drop into this thing with minimal work as long as you're handy with a power drill and own a vice and some punches. Look up barrel swaps on YouTube.
Another sponsoring business on this site should be able to get the barrel from the USA for anyone interested.
These are indeed designed for the US civilian market, as the barrel isn't even actually 16" long. The rifled part is much shorter, and only the pinned and welded flash hider sleeve is what gets this thing to the US legal length of 16".