Good to see this thread getting revived yet again.
Yorke and Jasent both inspired me to build a 338-375 Ruger. I actually bought my reamer from AZshooter. My build was based off a savage action. So far I've had great luck with 76.5 gr of H4350 and 250gr Accubonds, average speed was 2912fps over 5 shots and 3/4" at 100. I've put 40 or so rounds down the barrel but have some more loads ready. I tried 250gr Berger Elite Hunters 20k off the lands and the groups and speeds were all over the place. I have them loaded touching the lands now and 2k off so we will see how they do.