Septembers issue of Small Arms Review has a good article on Colts development of its M16 Automatic Rifle. The mechanics of the open bolt firing mechanism is pretty ingenious. Colt Canada/Diemaco further developed and produced a M16A4 type variant. Article didn’t go into the Colt IAR. Worth taking a look at. Their was a little more to the rifle then I initially thought.
I am diging that lower, I want that on my 6920… hehe
The Colt Rep at LAV’s Carbine class in Dec 2009let me have some trigger time on the IAR. Nice piece of kit and handled well in FA.
Here’s a pic of me with it.
Is that a Tan Elcan I see?
This one wasn’t tan- black ELCAN Spectre. Not bad but I prefer a Comp M4…
any pics of said lower?
What weight configuration was the barrel? Did it have a heat sink on the barrel? Any thing or interesting going on internally? Hydraulic buffer assy, etc?
Weight config of barrel- IIRC “heavy” contour under handguards, but don’t recall 100%. 
Heat sink- I think so.
Internals- Never broke it down or anything.
At the end of day 2, anyone that wanted to fire it was allowed to. I ran several mags of IMI M-855 and Hornady 55 grain practice ammo thru it, all full auto, and encountered zero stoppages. 
Not much help on the tech specs, but it was like 14 degrees outside and we all wanted to get indoors and warm up.
Thanks for the info, I appreciate it. For the IAR program to be a real success, depends largely on a ultra reliable high capacity feed devise. I hope the new Magpul 60 rd quadstack magazine.
What are the rollmarks on the lower?
The Colt M16A2 LMG in the article read: M16A2, CAL 5.56MM, Ser.#9159801. Selector markings, safe and fire
Yeah, let me see if I can dig it up:
