Answering questions like this depends upon so many things its difficult to have a set answer on some of them. Lots of things work some time, but depending upon the conditions may not work all the time. Lots of guys have used various cartridges and guns which have worked the only time they needed them so they assume it's perfectly good all the time. I think the better answer to the question should be what works most( or all) of the time. Not what worked the only time or two you needed it.
Put another way a .22 rimfire will kill a 1000 pound bull elk but it's not an elk gun. I'll do my best to answer these questions but several months from now if these questions come up again asked with a different spin or set of conditions my answer may vary slightly. One tool for every eventuality is difficult. However with that set of conditions you must always prepare for the worst possible situation in my opinion. I took the liberty of pasting your questions here so I could answer then below each one:
I realize a handgun is not ideal for the purpose, but for very large dangerous game like lion, cape buffalo, brown bear or moose, what handgun and load would you recommend for last ditch protection (i.e stopping a charge and/or shooting an animal that is on you)?
Stopping a charge is not gonna happen on the animals listed using a handgun so eliminate that from your inventory of choices! As I said above it may happen once or twice with a lucky CNS hit but it's an absolutely non functional weapon to depend upon. It will give you a false sense of security and put you into situations you would not otherwise have gone into unarmed. With a handgun you are effectively "unarmed" against those animals.
I have had a bear on me and been chewed at the same time I had a 44 mag ruger redhawk with 300 grain garrett hardcast bullets. I never was able to get the gun out of the holster to use it. Every Time I moved the bear bit me again and again. A brown bear lion or Cape buffalo will crunch you to bits long before you could use it by your statement of "shooting something that's on you". It may work to deter the animal but your really pulling the auxillary rip cord at that point. I think anything starting with a .44 mag would be better then nothing or a sharp stick but it's likely too late by the time you pull the trigger.
I remember reading an article offering a reward for any information proving somebody survived an attack by shooting a bear with a handgun after the mauling had started. To this point I have not heard of anyone collecting the money. The biggest problem with a handgun is that it's in a hip holster under your coat and you are on the ground with an 800-1200 pound bear that is chewing you up. Your hands are instictively busy fending off the bites and your hands get chewed pretty fast with defensive wounds. It's very difficult to open your jacket or pull it up high enough to get at the gun and then unsnap the holster to remove the gun( I know this first hand). In that amount of time your limbs will be ripped loose and your head crunched. Unless you have that gun in your hand at the instant of the attack I really see no functional use. Maybe in warm weather without a coat on, but even then you're in a bad way depending upon a handgun for help.
What do you think the advantages and disadvantages are for using big bore lever actions (45/70, 450 Marlin, 444, or 500 Alaskan, etc) for dangerous game defense (lion, cape buffalo, brown bear or moose)?
A lever action big bore is far better then any handgun. I don't prefer the lever actions and nobody I know in this business uses them for many of the same reasons I don't. However they are a long shot better then a handgun.
What do you think is the best big bore round for say brown bear defense, heavy blunt hardcast rounds or lighter hollow point partion rounds moving much faster, or a combination of the 2 (i.e. a fast moving hollowpoint to slow or stun the animal followed by heavy hardcast)?
If we are only talking about brown bears here I would choose a 270 or 300 grain soft point bullet in the 375HH. Brown bears are thin skinned and easy to penetrate. Their bones are not overly strong or solidly built like a moose or Buffalo of the same weight. Breaking the bones is critical in a charge or defensive act. CNS would be the first choice but it's a small and difficult target. Bears do have a lot of adrenilin and a strong will to live but don't have the body construction to withstand the bullet impacts that a Buffalo has.
The guns bigger then the 375HH are fine so long as you can shoot 3 shots quickly. If the recoil is too much for you then choose a smaller rifle. Several accurate shots are better then one you cannot hit with. Many times the first shot is deflected by brush or missed in the panic. A follow up quickly after the miss from a gun like a 375HH is better then the bigger bore which also missed the first time but has so much recoil that a quick follow up is impossible for the shooter.
There is a delicate balance between enough power and recoil recovery. That's why the 375HH is the minimum for this duty. The recoil is easy to handle and it still has good crumple power. Nothing smaller works as well. With a 375 diameter bullet you need 300 grains at 2500 or 270 grains at 2800 to work well. With .458 diameter bullets you need 450 or more grains at 2100 fps or more but not more then 2350-2400fps because the bullets will fail much of the time at the higher velocities. These are ideal numbers ofcourse. Lower velocities may work fine but as I said I am replying to these questions with what I know works the majority of the time. If you choose something less you take your chances.
Was this any help to settle things in your mind?
