Everyboby has problems firing prone with IBA and helmet on.
(How dangerous is your range that you're in kit but still playing with a bipod?) Otherwise I agree with TR - stick to the Harris and don't put it on a CQB gun. I have both 6" and 9" versions and only use them on my SPR forgery. FWIW I don't use them very often (I prefer bagging it or using a sling) but when I do it's usually the 6" on a LaRue adapter . Hint - If you mount it with the legs forward they won't tend to collapse when you lean into them. You can also flip down one of the legs and use it as a foregrip if you like that kind of thing. Yes, they do snag that way but it's not an issue for me - I don't keep them on when they're not needed. (The LaRue takes seconds to put on - and it's bombproof.) YMMV