I would say yes
I think it would sit a little bit too low without the mount, and unless burris makes a more suitable one I think you would want the one with picatinny mount. It would make it sit high enough to not be obscured by the knobs on top of the AR-536.
I think its the most versatile mount for the Burris Fastfire III, it can be taken off and put on anything with a rail. You really only need a different mount if you plan to put it on a handgun or something without a rail.
Its something to consider, if you get one you will instantly feel like it has a place on any platform you put it on.