Well Eddy, here's what I'm scheming

.... I had a chat with my gunsmith yesterday about a
300 WSM build I've contracted him to do and I asked him about nitride treating the barrel for better velocity and extended barrel life and he told me that it would greatly extend the barrel life, about 2-4 times.
Well this morning I had an epiphany about going with a 300-375 Ruger instead of a WSM

. I have also been wanting a 6.5-something and figure with a nitride treatment, I might get 2000 rounds or more from a 6.5-375 Ruger.
What velocity? I have had great results with RL17 and my 300 WSM and 25-06... 200 fps increases in velocity over other loads. And I think the 375 case is a good candidate for RL17. I plan to develop two loads for it, one with GS bullets (which are very spendy) and another plinking/fun load with maybe E-Tips or something. GS will develop a custom bullet to my specs, so I'm guessing about a 120 gr, high BC (.55-.6 ish) monometal pill. And GS bullets get about 100 fps (give or take) better velocity than other bullets because of driving bands and molly coating.
Sooo... If we look at Hodgdon's data for a 120 gr bullet in a 264 mag, they show 3300 with Retumbo. Conservatively add...
100 fps, RL17
50 fps, GS bullet
100 fps, increase powder capacity
50 fps, 5C rifling and nitride treatment
... which gets us to 3600 fps... and just maybe 3700-3800 fps.
All speculation of course, but I have little doubt that this will be a sizzzzling combo