There isn’t that much interest in full auto actually. I’m sure this applies to SBR Trusts as well, of which they must be getting deluged over lately.
Full auto is very wasteful of ammo, not really a good way to go, except in special situations.
Don’t know where you get the “there isn’t much interest in full auto” line. We do a booming business in rentals and the customers all want their own.