The .257 never caught on? Another brilliant post. The .257 was introduced as a factory round by Remington in 1934, and between then and 1955 (when Winchester introduced the .243) it was the most popular chambering in its class, which might be called the combination varmint/big game rounds. But the publicity surrounding the .243, thanks mostly to Warren Page, somehow convinced the public the .243 was far superior. It really wasn't very different than the .257, but between the PR and some inflated velocities for the .243 factory ammo (this was before average shooters owned chronographs) the .257 faded. But it did "catch on" in the 21 years before the .243 appeared.
On the other hand, I've been shooting both the .243 and .257 for years, and my wife has for quite a while as well. If there's any real difference in killing power between the two we haven't been able to find it.
Though I also must note that I've never had any troubles killing stuff out to 500+ yards even with short-action .257's. In fact used one as my back-up rifle when guiding deer and pronghorn hunters in the 1980's, loaded with the 100-grain Nosler Partition at around 3250 fps. (I was more of a hotrodder in those days, though the rifle never showed the slightest strain from the load.) Whacked a bunch of animals, both mine and a few previously wounded by clients, out to around 550 with no problems.
