Re: 7mm Remington Ultra Mag
Another bullet that works really good in factory RUM throats is the 175gn SMK. It is far more forgiving of the long factory throat. The new 180gn SMK is also as good if not better at handling a large jump. You can push either of these to 3150 to 3200fps with either Retumbo, H50BMG or 869. I know Kirby says he's not keen on H50BMG but we've fond it really useful in factory RUM's. It does get rid of barrels quicker than the other 2, but that means you'll get annew match barrel on their sooner!
Seat the SMK's out until you've still got 100 thou of parallel in the case neck, and they'll easily shoot under .5 MOA unless you got a real dog of a Sendero. If you seat them to fit in the mag, they'll probably still shoot ok, but they shoot more consistently seated out as far as you can with still 100 thou holding in the neck.
Once you rebarrel with a custom short, tight throat, then you have a far larger range of bullets that will work. The 7mm RUM is an awesome long range hunting round as Kirby say, so long as you don't treat it like a high volume varmint rifle!