I feel your pain; however, be assured you are not alone in having a custom rifle
built that dont perform to expectations. Frankly your problem is a dirty little secret no one wants to talk about. Especially the individual that has 4K in a rifle that dont shoot any better than his buddies wal-mart special. Im not just whistleing Dixie , Ive witnessed this happen several times.
I am wrestleing with a 308 barrel as we speak that was first built on an AR platform, ( manual operated, no gas port ) by a very well known smith. It shot groups around 1 1/2 min with occasional flyers opening things up to 2 1/2 min. I fed this all my pet loads and FGMM all etting the same results.
I decided it was just an AR thing so I had it built by another smith and put on a proven 700 action, stock ,scope combo. It still shoots like crap. The barrel maker blames the smith, the smith blames the barrel maker and they all blame the shooter. Even thouh the shooter can screw on another barrel and shoot under 1/2 all day long.
Sooo, the moral of the story is they dont all shoot well, if you dont believe that hang around a place whre the guys with all the 1/4 min rifles hang out and listen to the...... Well, it shot good yesterday or Ive never had it do this before and the list goes on. The truth is a consistant sub half every day all day rifle is not as common as one would believe by listening to folks talk or by reading about all the lasers on the inter-net. Hope you dont get too depressed by all this but it is the sad truth.