Re: 338 rum
When your primer raises like that its a pressure sign. I would say that you would do well not to go above your 93 grains.
I have a 26" barrell on my .338 RUM and with 94 grains Retumbo Im getting right around the 2815-2820 at my elevation. you should be running a little faster with you 30" even though a grain less charge.
I cant stress it enough, a chronogragh is seriously as important to long range shooting as a scope with turrets or hold-over reticle... you cant be effective at it without one (even though I've seen some old timers do some crazy stuff with ol' kentucky windage, still not great). I tried for a long time estimating my velocity. when I broke down and bought a chrony my game got 10x better overnight.
*EDIT* I have a "shooter" chrony, cheap but it works.