Just getting the parts/tools in line for my first build.  How will know if I have to grind the extractor down, and how much.  I plan on using global 1mm reciever on amd65 parts kit.

I presume you mean the Ejector not the Extractor. The extractor is on the bolt and pulls the shell out, the ejector is part of the rail the pushes on the side of the shell to make it fly out sideways.

get the whole thing built up first (trunion, rear block, barrel...) then take the bolt carrier (sans bolt) and fit it.

you will sometimes have to trim the upper rails a little to make it slide well. look especially on the UNDER side of the upper rail. GT has a tendency to use dull tools in cutting, and I often find a heavy burr under the upper rails. you think you need to trim the rails, but it's usually the burr on the under side. you can do this carefully with a cutoff wheel on a Dremmel...

once the bolt carrier (without the bolt) runs smoothly, add the bolt to the carrier and see if it clears the ejector. It ususally requires some grinding. I use a sanding disc on a Dremmel tool. Take it REAL slow, because if you take too much off, you will have unreliable ejection of the casing. for me it's usually only a few passes with the Dremmel before the bolt and carrier run smoothly.

Im sorry, i meant ejector, ive been hitting the kool-aid already today, thanks for the info.  I plan on putting this together soon.