Brian, for me it would be hands down the 45/70. Although I would use a 405 grain cast bullet. A well placed big bullet for terminal damage with sufficient velocity for penetration equals a dead bear. This not a tough decision in my book.
Jim
Yes, I see it like this...
1)I probably won't hit what I need to the first time.
2)I've seen modern, monolithic rifle bullets from "weak" calibers like .243 and 7-08 penetrate deer almost all the way *length wise*.
3) Bears really aren't any different than deer, unless you hit something HARD like the skull or shoulder. If you do that, it's a mute point because you've accomplished your mission (or most of it). I'm going to keep shooting any way until the thing stops twitching. I expect to be scared.
4)Nothing from a 22 short to a .50BMG is going to "knock down" or "stop" the bear unless it hits a vital structure.
So, what I want is not some hard to shoot round that kicks too hard and makes follow-up difficult. I want something that's making a lot of holes as quick as I can make them.
I'd rather have a full-auto .223 built for low recoil, loaded with TTSX than a .45-70 anything. You can have your one, or two if you're lucky, .45 caliber holes. I'll take my chances with 30 .223 holes.
Maybe if I was trained for it I'd choose something else. With no training, dropped into your scenario, I don't want an elephant gun that gives me one chance to get it right.
Besides all that, we are in the handgun forum and none of this "What rifle to stop a bear" really has the slightest relation to the forum or the OP.
Handguns of any nature do not have knock down power of any kind, stopping power is not the same as penetration and, all else being equal, bigger holes are better. Unfortunately, all else is never, ever, equal.
Hunter Customs said:
True it's not a physics formula, it's one man's opinion with a lot of real world experience.
That packs more weight then a physics formula with me.
The whole world, everything in the Universe from Quarks to Galaxies, operates by the laws of physics. Whatever you believe this man's experience was, it was all based on physics, whether or not he knew it or interpreted it correctly.
Hunter Customs said:
Bullet diameter should be part of the equation, I see no good reason why it should not.
I don't feel that just because his information took place 75 years ago that it's out of date.
Just because something happened years ago does not mean it's not useful today, after all we are still using gun powder.
The trouble is not that it arbitrarily happened too long ago, it's that things have changed and the formula has not. If it were a physics formula, it would not need to change. Because it is no more than one man's arbitrary creation, it may well need to change and, in fact, may well have no validity at all 75 years later, if it ever did anyway. We can't really know, because it's just one man's idea.
Bullets are not what they were 75 years ago. In most cases, the bargain basement bullets of today are superior to the best you could buy in the 1940s.
I agree that bullet diameter should be *part of* the equation but why PURELY diameter and why multiply momentum and diameter? (Because it gave the result he wanted, that's why)
What about sectional density?
Why momentum and not Kinetic Energy? Why not a formula that considers both?
Why does he arbitrarily divide by 7000? The answers would have exactly the same ratio without being divided by anything. Why not divide by 10,000, or 5,000 or 2,500? Why divide by anything at all?
Why does it not consider expanding bullets? (because the formula only applies to dangerous game where they did not and do not use expanding bullets and is really quite irrelevant to any other scenario)
Those are the problems, it's not because it just expired after 75 years, it's that it failed to adapt (and not being a "law" it may need to adapt), and it really only applies (was ever meant to apply) to specific and dangerous animals/situations.
Also note, that if you believe that TKOf is an accurate formula, you'd be better off defending yourself with a baseball than with a rifle of any kind.