Re: Custom 338 lapua rifle
Man, that is a LONG time to wait for a build. You can get a 1/4moa gun from a number of the reputable dealers here, and though it won't be guaranteed, you can certainly up your chances by listening to builders' recommendations regarding specs and parts.
I got a 308 from APA a year ago. With handloaded 175SMKs and 155 scenars, it will shoot bug holes, but frankly, I'm the biggest variable in the equation. I can't hold 1/4moa consistently (yet!) even if my rifle can with its sweetheart load.
Call up one of the builders and see what they're willing to do for you and what kind of cost it would take. Chasing that ever smaller group is a task for benchresters though, not tactical shooters. I will say there's a 338LM built on a TRG on the APA website with a test group to make you drool.