Take your .378 Weatherby. I own that and quite a few other Weatherbys in Mk V. And, the control feed argument, in my opinion, is simply a marketing ploy. In all my years I have never had a problem with a Mk V.
On the ammo issue, for the CCZ .375 H&H, if that is an issue simply drop down to a .375 Weatherby for it will also shoot the .375 H&H and is much more powerful than the .375 H&H. The .375 Weatherby delivers 5,224 ft lbs with a .300 grain Nosler Partition..
On the caliber, in Africa the minimum requirement in most countries is the .375 H&H. In others it is based on the muzzle energy. The .340 Weatherby delivers more muzzle energy than the .375 H&H. The muzzle energy delivered by the .378 Weatherby using a 300 grain Nosler Partition is 5602 ft lbs. It is also traveling at an mv of 2900 ft per second.
The .375 H&H topped with a 300 grain partition gives only 4000 ft lbs, some 1,602 ft lbs less than the .378 Weatherby. The .416 Rigby with a 400 grain Nosler Partition gives only 4,988 ft lbs, 700 ft lbs less than the .378 Weatherby. The .416 Remington Mag with a 400 grain Nosler Partition gives 5,115 ft lbs, 500 ft lbs less than the .,378 Weatherby. The .458 Winchester Magnum with a 400 grain Trophy Bonded Bear Claw gives only 4,495 ft lbs some 1,100 ft lbs less than the .378 Weatherby. Finally, the .416 Dakota loaded with a 350 grain Woodleigh Soft Nose gives 5,691 ft lbs of energy. But, for those who would argue to use the .416 Dakota, they should look at the .378 Weathery loaded with the very same 350 grain Woodleigh Soft Nose. The .378 Weatherby loaded with the 350 grain Woodleigh Soft Nose delivers a whopping 6,196 ft lbs. OUCH!  Â