Quick question...   What type of finish does Rock River use on their receivers, is it teflon or phophate or something else.  I need to know if it will match an armalite lower.  Thanks for the help.  

RRA has a flat mat black finish.

I does not match up to teflon coated finishes like that on the DPMS receivers (the sheen is different, but the color is the same).

I just went threw the same thing on a RRA lower that I got last year.  Ended up ordering a RRA stripped upper to have them match.  If you plan on buying a RRA lower, then you may want to just order a stripped upper to match, then order a parts kit minus the stripped upper to complete the build.

Unless you have already bought the lower, check with Eagle arms to see what he will charge for both a lower and stripped upper.  Chris has sales from time to time, so you may luck out and get the lower for around $90 and the stripped upper for around the same.  The pisser is when you have any of the kit suppliers deduct for the stripped upper from the kits, you end up with only around a $60 price reduction.

P.S. When I order kits, all parts are complete unassembled.  This allows me to fit all the parts as I build the rifle.  Unless you have all the tools to build a upper, you may want to check over the Hometown forum to see if anyone around you has the tools, and time to help you do a complete build from scratch.

It's anodised, just like everyone elses; but that won't answer your question.  Even though everyone is anodising the aluminum parts of their ARs (even the outfits that later Teflon coat them) the color will vary from batch to batch. Further, it's not just the color that varies. The finish quality of the piece before anodising will also vary. one will be shinier than another, or will have a different "tone" to it. (Sorry, I can't come up with a more descriptive word).

For example, I have an M4gery built on a Rock River upper and lower. There is a slight color difference and a little difference in the appearance of the two pieces, if you look at them from a slight angle under a strong light.  The only way I know to be sure of a reasonable (forget perfect) color match between uppers and lowers is to eake the piece you have to a dealer or gun show, and actually compare the pieces you have to the one you're looking for.