Going below 1 MOA at 100yrds

1. on the quality of my AR: How confident can you be if you mandate a gunsmith do build it for you?
2. on the match ammo: I will try Hornady Match, I hope it will make a difference.
3. on the really good shooter shooting the rifle instead of me: it will happen tommorow, I will get back to you with the results.
Thanks for all the feedback, I appreciate it very much.
 
I really really recommend you try a different scope, since you've verified the mounts are tight and you feel like you're not moving at the shot. If you have another AR it's usually pretty simple to swap scopes around to verify. Unfortunately scopes going bad internally is more common than we'd like to believe.
 
It's a brand new Vortex PST II 5-25x50. Of course it's possible that the scope can malfunction, but is it probable? No. I would rather think it's the barrel/receiver or handguard/gasblock issue. I will try to verify this in the first place.