I'm new to AR rifles, and I was wondering if this is a Pre-Ban Colt M4. Please excuse the beginner questions in my first post. Here's what I'm looking at:
Colt gray rifle, blue label box, model R6551, manufactured in early 1994. Lower is marked "Sporter Target Model Cal .223" Has the sear block.
The upper is A2, not a flat top, marked "CMB" on the handle, and has a tiny "circle in a square" as well. Rear sight wheel is marked "8/3".
Barrel is 16", has the A2 flash hider, and is profiled for a grenade launcher, has a bayo lug, marked "B MP 5.56 NATO 1/9"
Front sight has a "crown" symbol on the left side.
When I look through the vent holes in the hand guards, I can not see the gas tube due to the black metal shield inside - are these the M4 hanguards with double heat shields?
Bolt carrier has a "C"
I'm about to put a Colt collapsible stock on this rifle, so will this become an M4/A2? Or do all M4 rifles have the flat-top receiver?
If this is not an M4, then what is this called, just a "carbine"? Did Colt ship these uppers in '94, or is this a retrofit? Any explanation of the markings would be greatly appreciated.
Last question: I don't want to overpay for this rifle, so what would be it's market value in about 98% condition, with what looks like very, very few rounds shot?
Thanks for such an informative forum!