Re: 338-378 starting loads
The SMKs are hard to beat for accuracy.
If you seat the 300gr SMK long at 4.100" like my brother does, his throat permits it, his max load is 118gr H870 and groups well. Start low and work up. He's getting 3000 fps out of a 32" tube with the 300.
The X bullet is a good bullet to, some of the flatbases seem to shoot better than the boattails though.