This is a discussion on AR-15/M16A1 lower receiver within the M16 AR15 forums, part of the Rifle Forum category; Hi!
I have been wondering if this lower receiver is a real GI product or a fake.
I believe this forum will give an answer ...
That is the correct marking for an early M16A1 lower.
Later A1's and A2's kept the prancing pony but omitted the COLT AR15 lettering.
The original military AR's were called AR15's. The name was changed to M16 (USAF version w/o forward assist) and XM16E1 (Army and USMC version w/ forward assist) upon acceptance of the new contract in Nov. 1963.
My next step is to find out if the rest of the rifle is matching with the lower receiver.
What are main parts on which I should concentrate at first?
That receiver, like all USGI M16A1 receivers, is considered a fully automatic weapon by the BATF and as such falls under the rules of the NFA (National Firearms Act of 1934) the GCA (Gun Control Act of 1968), and other more recent 1986 legislation which highly regulates the manufacture and civilian ownership of fully automatic weapons in this country. In other words, they can't make them for us anymore, so consequently the ones that were manufactured and in civilian hands before 1986 are VERY valuable due to their scarcity. Citizens of some foreign countries are lucky if their governments trust them enough to allow easy ownership of these weapons!
The Colt markings found on that receiver appeared on the early issue M16A1 rifles starting around March of 1967. I'm not sure of exactly when they stopped using the AR15 logo on the M16A1 Colt lowers, but I suspect that it was somewhere in the mid 1970's.
You would need a USGI M16A1 complete upper, an A1-style buttstock w/ trap buttplate, a buffer tube, spring and extension, and an A1 pistol grip to build a correct USGI M16A1 rifle. All of these parts are readily available at reasonable prices. I built a US civilian legal semi-auto version last summer using a PWA semi-auto A1 receiver and USGI surplus A1 parts. It came out great.
Different anodizing contractors were used during M16 production so the colors can vary from the gray-green in your photos to a more common medium gray. AFAIK, none were ever originally finished in the more modern black that's found on todays A2/A4/M4 models.
The A1 "birdcage" flash supressor is correct for the receiver in your earlier photos. It replaced the earlier "three-prong" flash supressor used in the M16/M16E1 rifles.
Technically, the buttstock that lacked the trap buttplate came on the M16/M16E1 rifles. Also very early civilian AR15 SP1's. The M16A1 was supposed to come with the trap style buttstock, but there never was a definite cutoff date for these changes. In many cases they were gradual. It is quite common to find early examples of the M16A1 with the M16 buttstocks, three-prong flash supressors, and non-chrome lined barrels. Sometimes assembling complete rifles for issue to the troops didn't quite keep up with the availability of the updated components.
Your M16A1 is certainly of the correct vintage to have served in the Vietnam War.
I would suppose that it is possible that it was an NVA capture and consequently sold to the British but unfortunately I have no information about, and no way to research it.
The US Dept. of Defense would probably have records pertaining to which unit this rifle was issued to initially, and on what date. I do not believe that these records are open to the public.
I would recommend treating it as what appears to be a very nice (and valuable) example of a VN-era M16A1 rifle and would not go any farther than that. Putting that serial number into US Gov't channels might be opening a Pandoras' Box if you get what I'm trying to say