Re: Which 338???Who to build it?.
The 340 wby is an excellent cartridge and the best we had for a standard magnum action until the 338 RUM came out in 2001. The 338 RUM will fit nicely on your action and would be the better choice because of cheaper brass, no belt and 125+ fps gain. I have shot the 340 wby since the 70's and like the cartridge. It is as accurate as any if built right. If wby can't bring their brass prices under control they are just loosing out to these new cartridges that perform as well or better with no belt and much cheaper brass.
Predictions are difficult, especially when they involve the future