Ran over, I mean across, a retro rifle today. The lower appears to be aftermarket partial fence A1, but has what looks like real retro parts. Dimpled pins, many circle mag button, etc. It has what I think it a D stock, altho it could be earlier. The upper is Colt proofed, barrel is C at the muzzle, and MP stamped under the FSB. It has a counterbored front lug, but an incorrect pivot pin. It is a grey slickside upper, with black lugs. It has a chrome appearing slick side bolt carrier, with a Colt bolt. The bolt carrier has the solid FP retainer, not the hairpin type.
I know I am rambling, and I have to borrow a good cam to get some pics. My fone doesn't take very good pics. I haven't had time to really take it down to get a good eyeball on things, but I feel I got a good piece. It will fit right in with my other mostly retro Colt "M16". I have a pair of Nodak A1 lowers, but now it appears I need to get a slickside lower for this one.

     

That partial fence would be correct for a very early USAF Model 604., which that upper would work for.  A later 604 with a full fence would not have the slick-side chrome BCG.  I wouldn't change a thing, but that upper would also be the correct upper for a 602 Model.

Sounds like an early 604 build... take pictures of everything and if you need reference pics of certain parts, including a many circles button lemme know, some people have a hard time telling the difference between many circles mag buttons and A1 buttons. Edgewater buffer? 601 buffertube? Earlybend gastube? If that build has even 1-2 of those items, you scored huge. Many circles mag buttons are $100+ early bends are 70-100, 601 buffertubes are 80-150, Edgewater's 175-250. Sounds very nice so far.

Mag release is definitely many circles type, also has a dimple in the "arm" side of the release. It has an Edgewater buffer as well. Early style gas tube, non magnetic. Gas key is staked with 2 round marks. The charging handle is the small triangle style. The bolt catch is the early style with no tit on the bottom. I will take the stock off later today to look at the receiver extension to see what it is. I also want to look closer at the FCG to see what trigger, disco, etc is in there. The hammer is a standard semi-auto type.

Sounds like my early 604's brother, every part is identical except that barrel is way too late, the charging handle, and your upper is likely different.

I took the stock off today. The buffer tube has 2 holes close to the receiver, and no wrench flats at the back end. I took the PG off and there is a "C" up inside. The screw holding the PG on is a slotted screw with a safety wire hole drilled in it. The selector is a "no tick" semi auto. The trigger is open at the back end with a FA disco. I am beginning to think I got my money's worth on this one!

Looking forward to pics of the upper..

Should have a borrowed digi cam today to get some decent pics with.

I must be looing in all the wrong places. Sounds like some really desirable parts.

There are some of the same type parts in the EE, not mine. I am quite happy that these parts are on this rifle. It makes me feel I got good value for what I paid.

Retro Parts

Finally got some so so pics.

Let me be the first to say, "wow that is nice"

Unfortunately that's not the uber desirable 604 upper and it looks like a 1967-68 upper to match the barrel, early squarish round forge. Strange that the builder used premium parts on the lower and BCG but used a common upper and barrel. Maybe he had an expensive upper on there and tossed that on to sell.

That lower could be a clone of my Early 604's partial fence. All I can think of is he had an early XM16E1 or 604 upper on there and like I said kept the rare upper. Very nice score either way!