I've been trying to find the article to verify this, it might have been in Rifle magazine, but I believe that barrel nut is swaged on. I was reading the assembly procedure the other day, the "nut" and barrel are held immobile with a headspace gauge in place while the receiver is turned and threaded over the barrel. Then if my info is correct, the nut is swaged down tight.

I certainly could be misremembering this but if not that would make barrel swapping or removal somewhat more difficult.

Gunnery, gunnery, gunnery.
Hit the target, all else is twaddle!