I have read another outdoor writer who surmised that in JOC's day, just a generation ago, the elk acted differently. That is, elk were actually found out in meadows and open areas during daylight much more frequently than now because the forty or fifty years or so since have brought about an exponential increase in hunting pressure. His reasoning thus went that this was more favorable to cartridges like the .270 where an animal could be watched, taken in the open away from the timber when the angle was right and watched as it fell, hitting it again as was necessary.
I don't know if this has any merit or not. Maybe Ranch13 or others can shed some light on this.

George