The 225 grain Sierra Gameking is a seriously accurate bullet in the Whelen and can be easily reloaded to break 2700fps. I've used it for years in my Whelen. It has gotten really pricey lately, though. My fall back bullet is the Speer 250 grain HotCor, which can easily be pushed to (again) 2700fps according to the new Speer Handloading #15. I think 2625fps is maybe better with this bullet just for controlling recoil though, as it kills on both ends when I load it past about 2650fps. RCBS dies are designed to neck up 30-06 brass from the get-go because the round was a wildcat from 1922 or so until around 1988 when Remington started making rifles for it. Nosler, Remington (sometimes), Hornaday and Federal make brass for the round. I generally use the Remington brass, because I get around 8 to 12 reloads out of it. I also neck up range brass from 30-06, because I have a pretty steady source for it. I get maybe 6 reloads with it. A source for once fired brass is /
www.diamondkbrass.com, which has among other things the Remington test brass from the factory. The have a laundry list of calibers available.