Lou,
Several observations:
Yes, today's 6.5mm "match" bullets tend to shoot more accurately than "hunting" bullets--but there are plenty of VERY accurate hunting bullets these days. As an example, the most accurate bullet I've tried in my custom 6.5 PRC made by Charlie Sisk is the 129-grain Nosler AccuBond Long Range, which will consistently put FIVE (not three shots) into less than 1/2" at 100 yards. And the bullets used in my 7mm PRC shooting were Hornady 180-grain ELD-Xs, their "hunting" ELD.
I have also tried plenty of "match" and "hunting" bullets in the 6.5 Creedmoor over the past dozen years, in several rifles. The finest accuracy in ANY of the dozen or so Creedmoors I've worked with occurred with the 140-grain Berger Hunting VLD--in one of the cheapest 6.5 CM rifles I've worked with, a Ruger American Predator. It grouped just as well in that rifle as the 129 ABLR in my custom 6.5 PRC.
Also, while the SAAMI minimum specs for Weatherby throat diameters are the same as for several other 7mm cartridges, they are TAPERED and longer than the 7mm PRC throat--and the 7mm WSM throat is also TAPERED more than the PRC throat, which has no taper before entering the lands. I would suggest you look closer at the details of the throat dimensions of all those cartridges.
The other factor with the Weatherby Magnums, of course, is throat wear--which happens quicker with cartridges that size. I have written a number times about how well today's Weatherby Magnum rifles shoot in the past 20 years, but throat-wear is still a major factor after a few hundred rounds.
