I bought a Bushmaster Varminter last year to use at work. I am a designated marksman for my police department.  I have come to the realization that it is TOO big for my expectations of what I need an AR for. I deployed the other night on a barricade and was positioned approximately 40 yards from the front of the house with a 308 PSS and again I was wishing for something a little handier with a lower powered scope.  This rifle would be carried in my unit in a GOOD hardcase and also deployed in my duties a shift sergeant.  
I have decided that I want something with a 16" barrel and a 1.5x6 scope or similar, etc. Basically either a RECCE style rifle or a copy of  Dave Lauck's Perimeter Carbine(16" Varmint rifle with a low mount scope and lights on the forend).
I have talked with Bushmaster and was told that I can send my upper in an that they will fit a 16" V match barrel to it and retain the varminter forearm. This would be the cheapest way out ad would leave a lot of room to mount lights, etc.
  I have also looked at model 1's 16" varmint upper and have thought of it.
  I have also considered a Dissipator A-3 Upper and adding a BUIS and a free floated rail, hand grip, bipod, etc as funds permit and later if neccessary an aftermarket barrel.
 
 I would appreciate any replies from LEO that may use or have thought of this same type of weapons system.

This is what I use for the same objective, I also have an Acog to put on it depending on the situation


I used to use this one also, it worked out pretty good also

This is what I carry in my patrol vehicle for when I don't have the time/need for my whole system. Grab and go, ready at all times. For what it's worth, that is a M1S's 16" Varmint upper and it is a tack driver.