Unless you're in N. Kansas City, MO, you'll be building yourself an AR10 if you use Armalite gear, or a Large-frame AR if you use other receivers. A GAP-10 is built by GA Precision and I doubt they would appreciate anyone else building a rifle with the same name. I don't know if they have trademarked the name, yet, but they have trademarked other names in their rifle line.
Ok, not really as far as being special, but I do work at GA. If you get a rifle with a proof mark that looks like a mitten (or a mil replica ordered since I started), I built it. The proof mark was supposed to look like a boxing glove, but it came out looking more like a mitten.