There are a lot of places you can shoot controlled classes of weapons, of which the AR is not. Neither is an AK.
I shot a grenade launcher, IR scoped CCR, FNH SAW, NVG with a full-auto SBR from PWS just in the last match. I figure I had close to $250K of mil grade weapons in my hands as stage guns during the match. The FNH 3Gun match always has toys to try out.
There are companies that also rent out weapons to use. Using the semi-auto clone or trainer for most of the mil grade weapons is the cheapest easiest way to gain the platform familiarity.
A lot of 3Gunners are military and LE. The Marine Combat Shooting Team works matches and they are great guys. Several of them are foreign weapons instructors. If asked, they will get you squared away on the general manual of arms for several platforms. After a point, there are only so many variations on a theme and then you just go with what you learned on similar platforms.
You could always make Knob Hill your vacation for the year too.
