My concern on this matter stems from a previous encounter with a medium sized Black Bear. About four years ago I was hunting over a frequently visited water hole. As the morning progressed I came to the conclusion that I was out of luck for the day. I walked a familliar trail that led through a thick wall of timber in the attempt to flush what might be bedded down towards my partner on the other side of the hill. Upon return to my water hole a large black figure exploded from the bushes on the bank, ran up a nearby embankment, and glared down at me from about 25 yards away.Adrenalin came into play and I shouldered my Marlin, centered the front sight in the middle of the chest and took him off his feet. He rolled down the embankment and slammed into a Douglas Fir, and all was still. I jacked another round into my Guide Gun and slowly crept towards where I believed he had landed. The problem with this situation was the impenatrable manzanita forest that lay all around this water hole. As I cleared the obvious visual obstructions and came into view of the spot, he tore off into that damned brush dragging his whole front end like a loader with the blade down. I took two more shots at a target that I realy couldnt see and stood in astonishment at what had just happened. I heard him dragging himself through that brush for about two or three minutes and then I could of sworn that I heard him drop. As I reloaded my 45-70 my buddy appeared with much interest in the three shots that he had heard. We decided to let him bleed out for a while and talked over the recent events. After about 45 minutes of no sounds in the brush I was nominated to walk point. "What a Rush". we searched and searched for that bear. There was blood here and there. He zigzagged all over that brush but about 75 yards from the initial contact the trail stopped. No more broken limbs, no more blood, nothing. We were either standing right on top of him or he had somehow slipped away without leaving any sign. I was disgusted with the situation. I had never been un-able to find a downed animal before. We retraced and retraced but there was nothing. On the next day, still nothing. I have still not gotten over that experience, and have used it as a tool to improve my hunting practices. I have since come to realize several mistakes that were made that day. The biggest was taking a rushed off hand shot. I believe that that bear was probably hit in his left shoulder. secondly, I should have let him bleed out after the first shot. And last, I now have no confidence in the factory load that I was using. After experimenting with many of my personal handloads with every .458 bullet weight that exists I have come to the personal conclusion that bullet weight is vital for deep penatration on heavy game. That bear was hit with a Winchester premiun load, (300gr. Nosler Partition Gold at 1800fps). I asked around and found many accounts of large animals being maimed by light high velocity loads of this caliber. I now use a 420gr Cast Performance bullet at 1800fps for all of my hunting with the 45-70. Penatration is amazing and kills are clean. This lesson has effected my views on all of the calibers that I hunt with.