Hi Pete.
Well, I first need to say that these are my own observations..no more, no less. And I may be wrong. ;) Here we go...
First off, I think a well tuned (there is the key...well tuned) gun can have just about any chambering within reason and still do the job. Look at the chamberings that routinely win in HBR...30 Aardvarks (a 30-30 Improved), 30X44's, 30-47's, basic shortened 308's, you name it...it can win if it's tuned to it's potential. There is NO MAGIC CASE DESIGN THAT WILL GET AN UNTUNED GUN INTO THE WINNERS CIRCLE.
Given the limitations of the 6X scopes we shoot in HBR and VH class, the 200 yd. tuneup is crucial. It's also very hard to tune at 200 with a 6X scope, but that's what needs to be done. It's been my experience that a good 100 yd. tuneup will not be the best for 200..it will be close, but not quite there. Many times,things that don't seem to make a difference at 100 (neck tension, seating depth, powder charge..you name it) are easy to see on target at 200 IN GOOD CONDITIONS.
I also think that many 'tuneup' issues are bedding related. Stan and I just had a long discussion on the phone about this and he agrees. I'm not talking about the big bedding issues that show up glaringly, but the sneaky little bedding bugs that cover up our best tuning efforts just enough to make us think that "That didn't make any difference". when we are fiddling with neck bushings, seating depth, etc, etc.
In our part of the country, we're blessed to be able to shoot with great HBR tuners like Randy, Mike Bigelow, Roy Oines, Craig Nagle, Dave Green, and many others. If you're not 'on' when you shoot against these 'bad boys', you soon will be...'cuz you get tired of 'em stompin' 'yer guts out! ;)
Lots of great shooters up your way Pete...you're lucky to be able to shoot with guys like this.
Good shooting. -Al