I read everything Jack O'Connor wrote and really really wanted a 270 Winchester. I combined my want for a Weatherby and a want for a 270 and bought a 270 Weatherby Mag. I moved away from the 270 Winchester as my hunting partner for several years had one. We always had to track his elk a long ways! Maybe Hammers have changed that. I don't remember him ever having poor placement of his shots either. I shot several nice mule deer with the 270 Weatherby Mag. That was one gun I regret selling.
In my thinking there is no such thing as overkill. Dead is dead! When I was 29 years old, I was hunting with a guy who used a 243. He shot a nice rag horn bull. It was a 5 mile tracking ordeal.
In my late 30's and most of my 40's, I hunted primarily with a 45/70. Almost all of the time I grabbed the Ruger #1 loaded balls to the walls with a 400 grain custom LaPoint spire point. I shot a nice 6x6 elk at just over 200 yards with it and it was a "bang-flop." Talk about kick! I slowly gravitated to using the Marlin Guide Gun, and have taken 5 elk, 7 bears and 3 deer with it. My point here is "there is no replacement for displacement." The goal of almost all the cup and core bullet manufacters is to make a bullet that mushrooms to about the size of a 45! That is what I love about Hammers. Brian and Steve have taken the route proved by Elmer Kieth, and that is a blunt bullet kills. Thus the shedding of pedals leaving a flat faced shank that kills more effecively than a round mushroom. My 5 years of hunting deer with a 44 Mag. and a 45 Colt I found the Kieth style bullets to be most effective.
Why a Magnum? I'll give you three reasons. 1. They are much more flat shooting. 2. Flight time is shortened. 3. (I assume almost all of us on this forum are reloaders.) Versatility. You don't always have to load to the max! You have much more flexiblity in bullet weight. In my 300 RUM, I am only limited by my barrel twist. I bought a sample pack of the 199 gr. 308 Shock Hammers. They are so long, I just couldn't imagine shooting them in the 308 Winchester or even the 300 WSM. It is a RUM round. I can load the RUM down to 308 numbers, but I can't do a visa-versa! So that is why it is often a magnum for me.