Re: 7mmRM or 300WM
300 Win Mag.
Don't get hung up on speed. In a barrel length of 26 to 28", the fastest you're going to <span style="font-weight: bold">accurately</span> push <span style="font-style: italic">any </span> high aspect (hi B.C.) bullet is between 2750 and 2900 fps.
I've used and seen used every belted magnum variant from 6mm to 338. I settled on the 300 Win Mag for the following reasons:
1) I can buy Federal Match 190 grain SMK that shoots as well as anything I can load. I've duplicated the Federal load
(73 grains of H4831 SC if memory serves, don't pack this yourself without checking) and shoot as far as any practical match application will call for. Yep, it costs a little more than if I loaded it myself, but by the time I account for my labor, I'd rather call Midway and order a case.
Well, you used to be able to.
2) If you pack a 240 grain SMK over 75 grains of Western Powders Magnum or 70 grains of XMR3100 and shoot with any 7mm all day long. I regard this combination to be the most balanced cartridge/bullet/powder combination available. The 7mm is arguably overbore, but the proof is in the bullet impact.
In the end, go with whatever you like and work with it until you're satisfied. All this is just my opinion, but in the end, I regard this whole conversation as blondes vs. brunettes. Pick one and enjoy.
Wes
PS: In the end, any rifle chambered for any cartridge only shoots as well as it's put together. Loose barrels, bad gunsmithing, shoddy chamber (and believe me, factory Remington 7mms have the worst, most variable chambers I've ever seen). Whatever you pick, the rifle and its provenance are more important than the cartridge you have it chambered for. If you can't spring for a custom rifle now, start with a Model 700 Varmint or PSS; put on a Badger Base and TSR rings, and a SS 10X42 Scope. It's as close to quality on a budget I've seen (and done), and serves as a platform for a a custom rifle. After you've rung out the factory barrel, take it to a good gunsmith for action truing, bedding, and a custom barrel, and voila, you're in the big(ger) leagues. Again, good luck with whatever you choose.