No there isnt. Either you havent watched the footage, or you dont know what a 223 Bushmaster looks like. Which is it?
I'm attempting to locate the feed from the helicopter on the day of the shooting - I saw it live. I know a Bushmaster .223 inside and out and can tear it down and reassemble with a blindfold on - believe me, I know one when I see it.
Then why did the cop eject a shotshell from it and why was he cycling the bolt using a bolt handle on the SIDE of the weapon? All AR platforms use a rear charging handle. What was in that trunk was absolutely NOT a rifle and NOT AR-15 Bushmaster. I'll wager a paycheck on it.
http://www.youtube.com/watch?v=wLrxSgkqJQc
I believe it may have been a Saiga
http://ts2.mm.bing.net/th?id=H.4789155678850769&pid=1.7&w=248&h=54&c=7&rs=1
Here’s the video. Pay particular attention around the 0:06 mark, where the camera zooms in to show them ejecting a shotgun shell from the “Bushmaster” :)