After giving it some consideration for a while I decided to finally build up a retro rifle. I decided on a 604 because the slick-side M16's are the stereotypical (to me at least) Viet Nam rifle, and being a 20 year Air Force guy, I like the idea of having an "Air Force gun" in my collection. I already have an SP1 upper and correct (at least I think!) buttstock, handguards, and pistol grip and will use a 20" pencil barrel and NodakSpud partial mag fence lower. My question has to do with what style of parts are "correct" for the lower.

Did the AF 604's use dimpled hammer & trigger pins, fwd & aft takedown pins, mag release, and selector switch?  

Unfortunately I have no good reference books, I can't seem to find a definitive answer on the internet, and I've had no luck trying to search on the board. If any of you could point me in the right direction, I'd greatly appreciate it.

To the best of our knowledge NO production rifles had dimpled hammer and trigger pins..They are only seen on prototype rifles. As for dimpled takedown/pivot pins,mag release and dimpled selector,,yes they are seen on early 604s for sure. By using the partial fence lower,,you are obviously shooting for an early example.

Hey, welcome to the forum and always nice to see a first post in the retro forum!

I am doing an early 604 build myself right now (see here) Sorry for the crappy pics and lack of progress but I've been sick all weekend

I would say that a late 604 will be an easier build in that the parts are a lot less rare and thus cheaper. See here for the differences.

Thanks guys!

I actually followed the link to Retroblackrifle after a buddy of mine told me about Nodakspud's lowers when I mentioned wanting to build an early M16 clone. That's how I narrowed my choice down to the early 604 with the 3 prong flash suppressor. I think my confusion was due to the pictures of 604 rifles showed the dimples, but the way I read the captions for the detail pictures as the pins and selector weren't dimpled.

So, to get this straight, for an early 604 I need the following for the lower receiver:
-Dimpled Mag Release and fwd & aft Takedown Pins
-Circular grooved (as opposed to straight) Mag Release Button
-Raised end (with grooves?) Bolt Release
"Conventional" trigger, hammer/trigger pins, and trigger guard all finished in gray (as opposed to the black of most modern parts kits)

I also have what looks to be an unissued Type D Stock and a mottled A1 Pistol Grip. I believe the Type D is correct, but I'm wondering if the mottled Grip is or not. I can attach pics if necessary.

Doing an AirForce build..

They are all OVER the board.

Basically you can build an AirForce gun with
any period parts and still be correct..

This is correct for a partial fence 604 as the ones I saw had dimpled parts.  For grip mottled would be good but the backstory might be it was replaced with a later one so I wouldn't get hung up one using anything short of an A2.   If you're good with metal stuff, you can make a newer bolt catch look like the original style.