Don't really know about a civilian model but I saw what looked like a black ACR on the second volume of Magpul DVDs (Art of the Tactical Carbine). I had a doubt the first time but after seeing it twice there was no doubt it was a "MASADA-type" rifle.
It had a weird handgard looking like the MASADA one but without the holes for gas ventilation and was completly straight, no rounds forms like the MASADA.
Couldn't see if it had the full auto mode so I can't be a 100% sure it was a civilian model or prototype.
The ACR in its "army version" is equiped with RAS handgard and in FDE. Some long versions in black at the bushmaster (or Rem, don't remember) stand were at the shotshow with short Pmags (I'm not talking about the MASSOUD in 7.62 NATO).
There's a huge civilian market for this gun, or at least a large number of shooters are interested in it, so I think I'll be a little more optimist than my usual self on that one.