Are the barrel contours on Weatherby's Vanguard the same between standard and magnum calibers of the same bore diameter? For example, is their 30-06 contour the same as their 300 Win Mag contour?

Yes

http://www.weatherby.com/product/rifles/vanguard/synthetic

Click Specs

Sweet. I've got a McMillan stocked 257WBY right now and I've been feeling like I don't need a hot .25. Really dig the stock, and the gun shoots lights out but 75gr of powder just to squirt a 100gr bullet Usually when I pull the measure handle on that much powder its going under a 400gr bullet...

Everyone needs a 257 Roy....

And if I keep it that will be why. Though I have been looking at a Merkel K1 Jagd in 257WBY with an extra barrel in 9.3x74...

I really think the 257 would shine in a Remington Ti. I prefer the heavier Vanguard as a 300 Roy.

Maybe screw on a 340 Roy tube.

Brian Pearce had a write up on the 338 Win Mag a few years back where he used a Vanguard (or it might have been a Howa version) as his test rifle. He really liked the rifle and the groups reported in the article were impressive. Action + Reamer = 340 Vanguard...

Both of my Vanguards shoot LIGHTS OUT and are stock cept for trigger and McMillan.

I think I'll find one in 338.