Go with the 7mm Rem Mag. You just don't need more for shots that will not exceed 300 yards and I think you'll find ammo more readily available for this cartridge than the STW or RUM. I've had five 7mm Rem Mags over the years and they've all served me well. My latest one is a Sako 75 and I couldn't be happier with it. This will probably be my last 7mm mag, but it will certainly not be my last Sako.