IF you want to compete your gunsmith gave you good advice. Hunting different story.
Go to any of the 1k club websites and see what is winning and the 338 will not show up normally. (Ohio, VA, PA, Montana, Mo, NC, etc)
No one is winning with a 338. Problem is match quality bullets for the 338. There really are not any real good ones.
The 338s have to be sorted to high heaven for base to ogive and weight first to get a shootable number. The 338 SMK and 250 Scenar are the only two being used right now by anyone with the vast majority using the SMKs.
Steve Shelp posts here and you can PM him and ask him what he goes thru to shoot his 338 Yogi in comp. By far, Steve and Dave Tooley, have more experience than anyone shooting the 338 in the 1000 yard BR game. Steve is about the only one left shooting the 338 at 1k, now several use the 338 Lapua AI, 338/404 or 338/416 for one mile matches. However, the one mile record is held by a 7mm WSM
The 7mm has numerous high BC match quality bullets with Berger, Sierra, Carterucio and JLK both in the 168, 175 and 180 grain range.
Lot of cases can be used to make the 7mm a LR match gun and hunting gun. 300 weatherby, several RWS variations for example to name a few and more than several top notch LR smiths who have years of experience building both types and shooting them for LR hunting and 1k comp. Dave Tooley-NC, Bruce Baer, Mark King-PA, John Myer-VA, Leonard Baity-NC are just few and have the proven ability and all are "Top Recommened Gunsmiths" on 6mmbr.com. You cannot go wrong with any of those and they know how to build a gun to do both and be competitive IF you want to compete.