Introduced in 1958, the 338 Win Mag might well be the best of the original improved magnums based on the case used for the 300 H&H, shortened, with body diameter increased, to deliver good performance in standard-length actions. The 338 Win Mag can be compared to the 270 Winchester as follows: it launches 50% heavier bullets with similar BCs at about the same velocity; it therefore has a similar trajectory and delivers 50% more energy on target. That is no faint praise. Back in the 1970s, I was struck at the comparison between the 300 Win Mag and the 338 Win Mag, when equating factory-load performance. While folks lauded the 300 Win Mag far and wide as a superior elk hunting cartridge, trajectory out to 500 yards with a 200-yard zero showed the 338 Win Mag shot within 2-inches of the 300 Win Mag while delivering significantly more energy. I cannot see how any hunter would ever recognize such a modest difference in trajectory but the difference in delivered energy would be obvious. This is all to say that, despite the wide popularity of the 300 Win Mag, the 338 Win Mag was a far better big-game hunting cartridge back then and with the best handloads used in both that is still true today. I used to argue that if a 30-06 would not suffice, neither would a 300 Win Mag. The most logical next step up was the 338 Win Mag. I still hold that opinion. This is not to say the 300 Win Mag does not offer a lot to the big game hunter, obviously it does. The point is, when both are loaded with best components, the 338 Win Mag offers significantly more. As was a host of standard belted–magnum cartridges, this case was derived from the circa 1912, 375 H&H.