Well I decided to keep an early Nodak partial fence made of 6061 and do a early 604 build with her. I just want to check with the experts here to see if I missed anything. Mind ya'll I'm going for a early, transition look. Here is what I'm utilizing:
Nodak partial fence lower
Nodak slickside upper
chrome bolt carrier group
dimpled selector
transitional style bolt catch
triangular charging handle
green colored/painted furniture
improved three prong with grenade retention banana peel device

Is there any other dimpled parts that would have been seen on an early 604 or is that at my discretion?  I'd like to find a cast FSB but I'm not sure if that's necessary. I wasn't sure about the green furniture and really like the mottled brown finish that JT from retro arms works does so any thoughts?  Here is the green furniture that I have that I was considering repainting. Any thing I missed or more input?  

Dimpled take-down pins and serrated mag catch would work.  Technically, the green furniture would not be correct, nor would the triangle charging handle.  The cast front sight wouldn't quite be right either, although it might be possible. What barrel are you planning to use?

So........go with a mottled brown finish?  I was just going to go with a regular A1 profile but with a more modern twist. When where 604's first fielded?  As long as my furniture is green should I maybe just go with a "early"  603/XM build and then the triangular charging handle would be good to go?

http://retroblackrifle.com/

Poke around this website a little

Oh yeah......been there a few hundred times. They helped my get ideas for my SBR XM177 build. I guess I don't want to make a "frankenstein" but still want to go for a very early transitional piece. Obviously the receiver limits me so no 601 or 602 unless I again went back to the idea of getting rid of the receiver for a NDS slick side which wouldn't break my heart. I kind of think it's cool though having the partial fence lower made of 6061 though.

So I'm on vacation and alternating between cleaning the basement, restoring a 69 Triumph and researching this early 604 build. I'm cleaning out my part cabinet which has some M4 uppers and look what I found in the back. I forgot I had the old gal and tucked her away after I had her XM grey anodized when I got her back in 2008. So with this early 604 upper my plans on making a fantasy transitional piece is out the window and I'm going to make her as original as possible. The bonus and I never noticed is that she has the square forge!!!!

Great find!

"Find" is the funny key word. For the last few years I thought she was an A1 upper but it's dark in the parts cabinet and with the M4 upper next to her I thought the FA and the brass deflector were on the old Colt upper.  So.....what do I do about the green painted furniture?  Will removing the paint using acetone or DA screw with the finish on the furniture?  I don't even know how good the furniture looks under the paint.  Has anyone ever seen pictures of early 604's with green furniture in the wild?

Id strip it unless you want to try to sell it and just buy a black set.

Only 601's had green furniture and even then, not all 601s had green furniture.

Any thoughts as to what would be more gentle on the furniture?  DA vs acetone?  Also, I currently have a chrome Young manufacturing bolt but it has FA notches. Should I find a slick side BC or no bid deal?

Sand them lightly just to rough em up then paint em black.

The  "ideal" parts for that upper (1964-65 time frame) would be as follows:
Partial fence lower
Standard charging handle (gray) not the triangle one.
Chrome slickside bolt carrier (3/4 round gas key) and MP marked chrome bolt. Cotter pin type fire pin retainer pin and FLAT head fire pin.
Black furniture, type C stock, no drain hand guards. Mottled is an effect of time, use, and cleaning chemicals, NOT a type of material. For sake of argument, the black dye used failed and results are you see the flakes of fiberglass showing thru.
Any combination of dimpled parts, there is NO definite here.
Mvp marked barrel. If doing VERY early 604, a Mvp marked barrel with cast front sight base ,while tough to find would be nice,, but more likely an Mvp with forged FSB is correct.
Early bend carbon steel gas tube. Again getting hard to find so most guys use an early bend stainless steel gas tube.
Edgewater buffer
Buffer tube, again if doing very early wants to have the 2 holes up by the shoulder. otherwise standard gray tube
Transitional bolt catch is fine, again, no DEFINITE here.
As for fire control group, how anal do you want to be? As long as they are gray (and Colt marked), no one but you will know.
I think I've covered it all.
Oh and yes, the improved 3 prong. While most 604s did NOT have the banana peel grenade retainer, my buddy Nick has several period, in country pics of Airforce guys that do have the banana peel.

Thank you sir!!!!!

My pleasure. Be sure to continue to post pics as you go. We love "progress reports" here in retroland.

Is the receiver recessed under port door?  Doesn't look recessed in pic to me.  If not recessed,  it will be later than 64-65 IMO and possibly would have originally come with a few later transition pieces.

Recessed like it's supposed to match up with the mag hump on the lower?  It's not FWIW so still an early 604 upper just not an early, early 604 upper.  I'm almost wondering if a parked slick side carrier with a chrome key/bolt would be more appropriate for her vs a all chrome BCG.

Hard to say on BCG depending on what year you go after.  Early 66 probably still chrome.  Later 66 into 67 most any combo of parkerized and chrome pieces definitely possible.  Figure up to 67 probably only approximately 200K 604's produced and figure half would have been recessed earlier style and half like what you have.  MP 12 barrel more than likely less drain hole and forged FSB as they really didn't sell that well compared to XM16E1 and total production serial numbers include both 603-04 models and exports.  Really only a limited amount with serials over 400K for 604 until 68 and round forging.  Colt was  too busy making M-16A1.

Later type D and no drain HG's regardless.  Buffer tube probably modded two hole at that point in time.  Partial fence to full fence at late 67ish.  No or sub contractor only markings on FCG pieces.  Save you some coins on build going 66ish which would more than likely be correct for upper.  Hard to say what really went on at Colt in early years for correct parts and each day shows a little something different when provenance weapons are examined.  Most 604's were built when there was a buyer contract.  There is a site showing contracts and the individual sales numbers weren't really that high per individual purchase and were generally filled with parts they could scrounge up IMO.

Regardless very cool upper and pretty hard to find one that nice today.  Great foundation for a retro build.  I'd probably get most all the components that would have been available in time frame and swap them around at my leisure same as Colt would have done during production as wallet would allow.  Might have seen some dimpled pieces.  Later door and there were still chrome BCG replacement pieces in arsenal inventory into the 90's.

Scored a great barrel this week and received her in the mail today!!  The seller was swearing it was a chrome lined M16A1 barrel but my "trained eye" noticed other things. I think she'll go perfectly with my 604 square forge upper. As ya'll can see it's a MP 12 marked barrel with flash removed forged/no drain hole FSB. Seller even threw in what he referred to as the original handguards of which one has no drain holes all for $400 which I thought was pretty good. The crown/bore look great with no pitting in the lands/grooves but it looks like a drunk monkey tried driving out the taper pins. In the picture straight on of the left side of the FSB it doesn't look pretty but there was no crushing or distortion as you can see from the front end of the FSB. I'm thinking I'd like to get the old taper pins out or at least the front one and renew it. Any thoughts to having it reparked? Here are some pictures.

Great score!

Good eye!

So........any thoughts on getting at least the FSB reparked. The bare metal of the front taper pin and surrounding area of the FSB is slightly unsightly.

When you get the fsb off, you can or John Thomas can clean up the mangled areas and re-park it. A dremel sanding wheel/drum (the narrow one) works good for steel.  Also you could Norrells just the repaired area and try to blend it close to the original color and keep the top half untouched. Norrells is cool because you can bake it longer and hotter to get a green hue. Nice looking barrel

Swing in direction of uppers. Going to use this one now and going for the 1964 look. Question on bolt, bolt carrier for the hive. As seen in the picture I have a mint old Colt 3/4 round key BCK and a Colt MP marked bolt. From what I have read this would be correct unless I'm mistaken. My question is what kind of firing pin should I use and will a regular parked bolt cam pin work or do I need a chrome one?
PS
Disregard MP 12 barrel pictured above.........going to use the M VP 12 w/ cast FSB now.

Very nice. The correct firing pin would be a flat head. Not the big head like the one on the 601 and not the current one. There are some good comparison pics if you google it. Nice carrier!

Thanks for the reply.  Would a regular cam pin work or do I need a chrome one?

Regular cam pin. They didn't use chrome cam pins.

Oh....my bad.  I thought 601s and 602s had chrome cam pins and figured some may have carried over to the early 604 builds. Now I see there were never any made.  Thanks

How far off would an MP C barrel be for an early 604?

The chrome chamber was added as part of the A1 improvements in late 1967, and 604 production started in 1964, so about 3 years.

If you have an MPC barrel you'd want a round forge upper, parkerized bolt carrier with forward assist cuts, and full fence lower.

All of the above, and the worst part: a birdcage flash hider instead of a 3-prong… Nooooooo!!!

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I did one of these with a barreled upper that I lucked into at a show. I started off being very strict about original parts ,but cut some corners along the way (thank God for HeatnBeat!!!!!!) Lots of fun though!!!!!!

Holy thread hijack batman.........