I am having Bruce Baer and Joel Russo build a 338-408 on a new Stiller 408 action.
Jerry is making them in a 1.450 and 1.60 diameter and in single shot or repeater. I got a 1.60 single shot action.
IMO a repeater in that case is definitely not needed. You are not in a tactical world where sustained fire is a requirement so why add $500 Plus to the cost of the build when you can reload just as fast for two shots with a single shot.
Big actions require big stocks, Joel Russo has an A5L (large diameter actions) what can accommodate what you want. Pick any kind of wood or laminate you want.
I went with a 32" Bartlein barrel that is 1.350 for five inches (gives me one setback and rechamber) and tapered to .950 at the muzzle and fluted. Cost was $611 shipped.
Brake was the new Holland Radial. Cost is either $100 or $110 and the one on my Lapua AI is absolutely the best brake I have seen, bar none., especially for big bores.
40 MOA base and Jewell trigger set at 1.5 lbs.
Stock will be exhibition grade bubinga with modified A5L. removabel sling studs front and rear in metal bushings.
Bruce is doing the chambering now and Joel is working the stock, hopefully can pick up in early sept at latest.
I believe Bruce had the first 5-6 Stiller 408 actions shipped and might have one or two left. www.baercustomrifles.com
Bruce also has a resize reamer to match the chamber reamer and can make a set of dies for you.