I'll say this one more time. I once watched an Inuit (back when they were still called Eskimos) elder stalk and shoot a polar bear. His rifle of choice was a 1951 win M94 in .30-30. One shot. About 60 yds or so. Knocked him down and he was dead in a few minutes.
One of the younger men stood ready to back him up with the "high-powered rifle". A #4 Lee Enfield .303Br!
I was in the local shop two seasons ago on opening day. Guy came in with
a .300 WM he had just bought 2 weeks before. Put it on the counter and said, "Gimme that .338. This thing can't even drop a deer!" and right there he told us how he had hit a deer at 300 yds, knocked it down, and it had got up and run away. Obviously, deer are tougher than they used to be. Comes down to shooting! You can kill a deer, moose, even a polar bear with the .30-30 but it requires skills most of us do not possess. Like patience and practice. A .398 Kawabunga Magnum allows you to be less persistent in perfecting your craft and let's more ordinary people make those perfect Texas heart-shots at 900yds
Case in point. This past elk season. My buddy listens to the hype of the Superformance ammo. Decides that is just what he needs for the upcoming elk hunt for the .300WM he bought for last year's deer hunt. He bought the rifle and 2 boxes of Federal PowerShoks. I sighted it in for him. It shot toonie sized groups at 100yds. He took it home to practice with it. Never got a deer, but never shot at one either. So, this year he buys two boxes of Superformance ammo and a new scope. We try to sight this in and this year I refuse to do it. He is all over the map, even with a leadsled. The rifle really did not like this ammo for him. So he takes out a part box of PowerShoks (10) still in it! Fires a three shot group that was about 1 1/2" and says that the ammo is crap. Then he buys another box of PowerShoks and asks me to sight in the rifle since time was short and he didn't have another day off before we left. I sighted it in, toonie size again. I told him he had to shoot it to make sure it was right for him.
He shot it all right. 2 rounds at a refrigerator at unknown distance in a gravel pit. His shot on an elk at 250yds was less than stellar! 8hrs of tracking later and we found the world's toughest elk!! Shot through the brisket! Had he known where the rifle shot, he would have killed it in the field When his second round creased the skull between the antlers as it ran away since it was still 3" high at that point. He is convinced that he needs a bigger rifle for next year since the .300 didn't do the job. Not more practice, a bigger gun!