The .30-06 is popular almost everywhere, including, apparently, South Africa, home of today's Savage 110. It has been around for over 100 years, of course, and continues to lay out creatures great and small. The .280 Remington was introduced in 1957, had its name changed to 7mm Remington Express for a while, then went back to its original name. Stuck in the niche between the .270 and the .30-06, much as the 16 is wedged between 12 and 20, the .280 is too good to ever go away, but it will never achieve mass popularity either.
Here are the rifles: