Welcome to the builders club. Be warned, it's like malaria. Once you get the bug, you never get rid of it. It may go dormant for periods of time, but it always comes back...
Sherluk does have some pretty good quality parts. They've even had some older M16 parts in the past too, not sure if they still do.
If you ever feel like trying to get a really close retro copy to the original M16's moses, you might want to check out the lower receivers that Nodak Spud is offering. They're pricey, but they are as close to the original M16 lowers as you're likely to find. Here's a link:
http://www.nodakspud.com/
Here's a few pictures of my semi-auto A1 that I built on a Nodak Spud NDS16A1 lower:
Hybrid Mode
