Re: At whitts end with .Sendero .338 RUM load development.
I don't load for 338 rum but do for 7,300, and 375 rum. I would second a vote to try RL25 and IMR 7828.... also, I have had some good luck switching to rem 9.5 mag primers when a load is not cooperating with fed 215. Also run your overall length at maximum magazine length if you plan on using the gun as a repeater and not having to single load the cartridges. This is usually somewhere around 3.670 on the rums I own. Make sure your reloads are concentric. Maybe check the crown of your barrel. Run your loads on up towards max. Rums can shoot well right up around max charge. This would probably be somewhere in the neighborhood of 3000 fps with 250 gr bullet. Check manuals to be sure. Hope you get it figured out. Nothing sucks worse than a new toy that doesn't perform.