Larry,
I went to RL22 in my 338 WM. Something else I do is use the 250 gr. that I bought in the time frame your having problems with. What I am thinking it isn't the powder or the load, I think the center of gravity in the light bullets has them unbalanced, expecially for your barrels rifling. Light bullets and heavy both really get optimized by different rifling twists. Have to admit that for a fat bullet, the 338 has some enormous weight deviations. Thats one of the reasons I usually use the heavier bullets in whatever caliber I shoot, heavier bullets seem to take to bad twist rates better. I look at the lighter weight bullets and start thinking of tossing marbles from a rocket launcer. What your telling me, I think I will just keep on using my heavier slugs.
Man, do I EVER sympathize on the cost of testing loads with those bullets, really a bummer when money and a plan don't work.