How much power is enough?

I will try to relate my take on the issue. For many of the years working as a timber faller in south east Alaska when we were allowed and often encouraged to carry a gun I almost always had a 44 mag with me. Because heavy loads cause me to become a flinching blinking fool I always down loaded slightly the 250gn Keith bullet to about 1000 - 1100 fps. I all the years I did this work I had to kill one bear in my strip but I will also say that I ran from several.
On the one occasion that allowed me no retreat I had with me a Ruger Red Hawk 5.5" 44 mag loaded with Elmers load or very close with 21gn 2400. I was working on treacherously steep ground in very big timber. As I progressed uphill in my strip I would keep tossing my pack containing my tool. food. and gun uphill and work my way up to it. My saw had been getting out of tune so I looked for my pack to get the small carb tuning screwdriver and I saw a bear standing on my pack ripping it apart. Knowing I needed the gun in that pack I picked up a thick spruce limb from a tree I had just felled and limed I went the few yards uphill to the preoccupied bear and with as loud as I could yell and as hard as I could swing hit the bear square across the back. Though it likely hurt some I think it startled him more and he ran about 20 yards or so then stopped and looked back. In the meantime I got the 44 out of the pack and put the red ramp front sight on center mass. The bear looked me right in the eyes , laid his ears back and headed right back at me. There was a root sticking up about 10 yards from me which I mentally noted as the point of no return. When the bear reached that root and was obviously still coming I fired the first shot single action which was a head shot because at his approach angle his head was center mass. I believe I saw teeth or brains go flying as the bear went up and over backwards. With the steep hillside and his momentum he continued rolling downhill untill he stopped at the las tree I had felled. As he was in motion rolling I continued firing three more shots in double action, something I thought I would never do with a 44 mag. Anyway on that day and circumstance the 44 was plenty of gun.
After that experience I though I had need of more gun so got a Freedom Arms 454 Casull. What I found with that gun was that the fit was so tight that after being carried every day for a few weeks when tried it wouldnt work. It was jammed up tight with normal field debris and no better than a rock.
After that I went back to a dependable Ruger single action in 45 Colt. A 45 Colt loaded to near magnum level in a dependable launcher seemed a good idea. While guiding for caribou near Alaskas west coast on the MUlchatna river I had a chance to prove its worth. I had lots of caribou to pack in to camp from the previous day as well as taking two clients out on this day. Because I had lots of packing to do I left my rifle in camp and only carried the Ruger 45 Colt. One of the clients took several shots at a bull at about 300 yards with a 7 mag but put every shots right in the guts. The caribou was walking into a stiff wind and the client even though his rifle was sighted in was not allowing for any wind drift . After several shots the boo laid down but was not dead. I told the client he had to finish the caribou but he refused saying he didnt want to ruin his trophy. Much to his objecting I told him I would have to finish the job so started walking toward the caribou. When I got to about 25 yards or so the boo stood up and started walking straight away from me. He had no run left in him but he was on his feet walking. I looked back at the client and he was paying no attention but saw my packer watching through binoculars. By the time the boo was about maybe 40 yards I pulled the Ruger and aimed at the center rear and fired. At the shot the caribou pilled up. When my packer came over to get started on the caribou I asked if he watched the shot. He told me yes he did and said when I shot he saw the hide on the chest stretch out and the a puff of hair. The bullet hit the ham right beside the vent traveled lengthwise through the caribou and still had enough energy to punch through the hide on the chest. My load was using a bullet from a Saeco mold for a 300 grain Keith bullet and the load clocked at 1000 fps at about 20 feet from the muzzle. After that I had great confidence in the Ruger 45 with a load that I could manage well. Same goes for any handgun that is first of all dependable for field use and that is capable of hurling 250 to 300 grain of lead at 1000 to 1100 fps. Regardless of what the ballistics are there is still the requirement to place it where it has to go. In a very tense moment that is maybe easier said than done.