Zep,
I haven't played with the 250's as yet. I've made the focus of my efforts the 210-225gr slugs. I'm pushing the Barnes 210XLC out at 3250. Sort of a long range sledgehammer in my opinion. I don't doubt that the 338/378 shoots a bit flatter, or hits a bit harder, but I will stand by the statement that you'd have to be a expert or better class marksman to even use the power of the .340 in the field, let alone the 338/378. If you can't get it done out to 400 yards with the .340, which is way beyond most hunters ability in a field situation, the 338/378 isn't going make it happen. I understand the idea that it's the last day on your $8K trophy elk hunt, nearing dusk, and you've only got a raking shot at 500 yards to take the "trophy of a lifetime" marketing scheme. Personally I think that kind of shooting for 99+% of hunters is pure irresponsibility and the height of unethical, so called, hunting. The odds that something will go wrong under field conditions with this mentality are FAR greater than the odds things will go right. I also understand that a 50 yard shot can cripple an animal if not properly placed, but at 4-500 yards where these cartridges shine, the odds are a hundredfold greater that a lost animal will be the outcome. So, since I think the shot is irresponsible, I don't see the need for the greater power. I'm not condemning anyones hunting style, or their choice of cartridge, but I fail to see the real world benefit or the ethical argument for this type of shooting at game animals. If you can do it 100% of the time at 4-500 yards where the cartridge has it's benefit, the more power to you, but I'd like to see guys who spout about this put 5 shots into 8" from prone with a sling at 500 yards...every time they practice, let alone with a increased heart rate.
As far as the Weatherby rifles, they are nice, but I don't see the value. I'm know the muzzle brake is effective, as I said I shot the 30/378, but I don't use hearing protection in the field and will NOT use a muzzle brake without hearing protection.