Weatherby decided they wanted a high performance 6.5 cartridge that could run through their smaller 6 lug action, but that action is .375 H&H length, not 30'06 length. So what was the point in designing a cartridge that is really too short for the action? Why not take the 284 Winchester case, at 308 length, and stretch it all the way out to .375 H&H length and stuff that into the 6 lug action?
Too much case capacity? Weatherby didn't think it was too much when they trotted out the 6.5-300, so that can't be it.
That just leaves the door wide open for Remington, Winchester, Nosler, Savage, etc to come in over the top of them with a longer version and leave Weatherby in the dust.
Tony Rumore