Hi
@Kevin Peacocke , I’ve never hunted with a .410 bullet but have hunted with large bores and 375s in equal measure. Echoing what the sages of old like Pondoro Taylor noted, anything over 40 caliber that leaves the muzzle at 2100fps and up, and hits an animal at 1900fps or more, seems to have a significant lethality advantage.
If we assume this commonly repeated wisdom over the past century is true, the big question is “why”.
If I had to assign cause for the consistent observation they just work better, I’d think of the following:
The 375HH and the small bores are relying on speed, or put another way, hydrostatic shock, for part of their killing action. The bullet doesn’t really do all the killing, the gas cavity does a part of the sheer and hyrdostatic damage.
The .40 caliber and up whether 404, 450, 416, 458, or 470, is not really flying fast enough to rely on the method of death the 375 and smaller relies upon, at least in part. The 40s are using concussive force of a big old piece of lead, and punctuating that by making a larger hole that results in faster bleeding and less likelihood the wound can close over with fat instantly.
While not a perfect example because it was a 7mm bullet, my son shot an eland through the heart with his 7x64. It was dead in 200 yards, but literally, not one drop of blood. Not one. The fat and skin plugged that whole instantly. I suspect a 375 is more likely to have that circumstance occur than a true large bore.
This is all conjecture, not science. I’ve not hunted with a 450-400 nor a 404 Jeff but I would not hesitate to do so, they are just overpriced right now as the “in vogue” cartridge. I just bought the “out of fashion” 375s, 416s, and 470s because there is nothing wrong with them and they trade at a fair discount to an equal gun in 404 or 450-400. I’m sure I’ll own them both eventually when the market fad for them dies out and prices align to their respected bretheren Calibers.