Who sells reloading dies for the above caliber?

The few RCBS dies that are still out are incorrect for the typical 338WSM. Most are actually 338/300WSM's. There aren't any of these dies "on the shelf", but both Hornady and Forster can make them as customs. On the Forsters they polish out the neck of a 300WSM die and they've got it. Hornady will make them off the reamer drawings for whichever reamer was used on the chamber. Or, you can buy a bushing die from Redding in 300WSM and use the 338 bushings in it. The top of the die just below the bushing must be polished out about .006", but it works well.

For seating buy any Hornady seater with the short body, such as 22-250. Then you can order direct from Hornady the 338 sleeve. Swap out what ever sleeve is in the short body and you have a seater.

God! I would hate to be the guy who has to polish the neck of a 300WSM die out to 338.

Why? It's only .015".

Are these dies surface hardened? Most are. .015" would be a lot of polishing. Use of a reamer would be better.JMHO

Redding makes 338/300 W.S.M. dies. I just purchased them from Graf. They had the F/l and seater. I want the micro seating die next.