Quoted:
If you did have a receiver, or a gun with shitty parts that you wanted to upgrade or rebuild, how much money would it cost to completely rebuild the rifle?
would it be best to strip down a 6920 and sell the 6920 receiver, or would you buy all the parts seperate?
how much would usgi FA FCG parts run?
Somebody said that a striipped reciever would be only $500 less, but it's hard to imagine building a decent quality rifle on a reciever with only $500
First, my recommendation is whenever you buy a registered receiver, you immediately strip it and replace everything with new Colt FA FCG parts. They are not only milspec, they are made to a higher QC level than most other USGI replacement parts. You can get them from SAW, Dennis Todd or Brownell's. I just got a full set from Brownell's for under $100.
As far as how you configure it, that's up to you of course. But if the receiver isn't Colt, there is no reason to stick to Colt uppers, stocks, etc. Just buy top quality.
If you are buying a transferable, every part on it is prolly at least 26 years old. Springs lose tension, parts wear, etc. That's why I suggest you start from scratch. And as far as uppers and barrels, full-auto takes its toll. So I wouldn't pay more than $500 more for a complete gun over a receiver, because I'm going to throw out everything except the receiver, anyway.
Now, if you are buying a factory full-auto Colt, I do the same thing –– but I carefully label and pack away all the original parts, so that if and when I ever decide to sell, I can restore it to original condition. My replacement parts take all the wear-and-tear.
HTH. YMMV.