Ah, the Bushmaster AR C-15 Ultra Lite. I purchased mine as a winter project to dress it up and change and see what I could do with it. It was inexpensive ($599.00) and I had high end AR's so I was not concerned as to it effectiveness. It came with a Bushnell Mini Red Dot, 2 - 30 round mags, a half inch riser, sling (cheap) and a hard case. Not bad for the price.
I too had the funny feeling about it being a plastic gun. Well sometimes you win and sometimes you don't. This time I guess I won.
The only two parts that are Carbon Fiber is the upper receiver and the lower receiver, all the rest of the gun is standard AR parts (metal) with the exception of the handguard and butt stock. The fit and fuction is better than a lot of metal AR's I used and except for the weight (5.6 lbs) you can not tell that it is Carbon Fiber gun.
If it wasn't for the fact that I have used and own a number of plastic handguns (Beretta PX4 Storm, FNH FNP-40, Taurus PT-140, Ruger P-97) I too might have passed on this gun.
Well, to make a long story short, after changing what I wanted on it ($165.00 additional) it is my goto self-defence (fun) gun, if I wanted or need to, I can change out the two carbon fiber parts for very low cost (not needed).
You can get the M&P Scout for around the same price (all metal) but I like Bushmaster and their accurate barrels and chambers (all else is just add-on's and pretty much the same.)
But for $400.00 less (than most AR's) you can not go wrong, just check out the gun completely before you buy.