We used to play indoor private games with wolfpack MB, "terror tuesdays" officially 400fps limit, but I know for a fact some of their guns were 500+ lol
Nobody had any complaints anyway, but I definitely wouldn't allow outsiders in on the games.
Also, safety? cleanliness of facility? LOL
The most dangerous fields are often the best! CFB rivers was ridiculously dangerous but one of the best fields for CQB. Real CQB too, building to building, with REAL buildings, none of this indoor maze crap.