Apparently there are a couple registered, KevinB was trying to get one a while back, don't know how that went. I'd imagine he has the most exposure to them. I'd very much doubt you'd be able to import one now, they are almost poster children for what USDOS doesn't want to see exported. Note that it is a US export prohibition on things like telescoping stocks, bayonet lugs and flash eliminators that gets in the way, the same as every other AR. Knight is highly unlikely to produce an AR without these features, since they sell every unit they build anyway.