At hunting ranges can't imagine what the difference would be.
The only difference for me is that I was offered a trade for a Roy rather than the 6.5... if it'da gone the other way, I'd have jumped on that, too.
My Vangard is pretty freakin' accurate and squeezes enough from RL22 in that "little" 24" barrel to make it worthwhile over my 257 AI.
I love it.
Oh... and you can easily form 257 WM from either 264 WM or 7 RM brass, so that is a non-issue.
