I have a buddy with an HBAR 18" that he runs suppressed. we were pinging steel gophers at 300 yards with cheap ammo. I'd suggest that. Even with a 16" heavy fluted barrel, I'd expect you could still get hits on target on 'Yotes.

NOt sure if it'll help you make your decision, but My thinking is this: If I can't think of a good reason why I need a barrel that long, then I don't really need it. Perhaps that will serve you as a useful yardstick as well?