Okay, call your buddy and tell him NOT to spend another dollar yet!!!
You have a "custom built" rifle and you were firing the worst shi*ite ammo out there, so chances are good his gunsmith is going to look at you with a "WTF?" look on his face.
First things first. He sent 100 rounds of brass downrange without incident. That means the thing was functioning before you introduced the rough ammo (think of the worst rot gut booze you ever drank and the after effects, that is how your buddies' AR is feeling right now
He needs to thoroughly clean the chamber, the throat, the BCG and really do a good job. He needs to get in there with an old toothbrush and scrub that thing out like his first set of custom rims.
From there he needs to take it back to the range with brass rounds and shoot it.
there are problems, only then can he go back to the gunsmith.
I am betting if he does as described he will find that it functions as designed.
sniper03 had a very good point about the chamber. I would bet it's probably 5.56 or at least Wylde, but it's something to check into if the 2nd brass shooting goes awry.