I am testing another powder that is a little faster than IMR4350 if any of you have an idea on what powder to try next let me know.I'm thinking W-760 maybe.Here is the run down so far....

16.5" 300mag

180gr Speer SBT
70grs IMR4350
2680fps

180gr Speer SBT
59grs IMR4064
2597fps

165gr Speer Spitzer
71grs IMR4350
2687fps

165gr Speer Spitzer
61grs IMR4064
2702fps

BTT

T/C NUT

Sounds like your are getting about what I was getting in my XP-100 300WSM before I had it rebarrled into the 300 RUM.I was using WIN 760 in it and that powder seem to do a lot better than anyother I had tried.
I am using IMR 7828,Hogdon Retumbo,and RL-25 in my XP.I think the Hogdon web site as some info on the 300WIN MAG with heavy bullets and Retumbo.

Im using H4895 in my 300 Win Mag 15" M/T barrel. WW Silvertips 150gr-2949fps
Speer Grand Slams 165gr-2833fps
I've tried several slower powders but so far the best has been H4895 in my barrel.

RWG you have PM

T/C Nut you have PM.

T/C Nut,
Finally chronographed My 7.82 Patriot XP-100 with 180 grain Sierra Game Kings during the clinic. I am running right at 2725 FPS at the muzzle. Actaully it will be a tad more but I haven't figured the 15 feet difference yet from the chronograph.
It sounds like you have a winner with your 300 Win. Mag!
Ernie

Yes, I think it was worth cutting it down.I got 150's going 2870fps with 64grs of IMR4064.It is a lot of fun too. I also got a 16 1/4" 45-70 I'm playing with now.