Yep.
Right after the .300 WSM appeared I noticed the appearance of far more used 7mm Remington Magnums in gun shops, as the boys traded off their rifles chambered for the In Cartridge of the 1960's and 70's for the first In Cartridge of the 21st century.
But I'm still seeing more 7mm RM's on used-rifle shelves, even though the .300 WSM's peak of hot selling passed years ago. I'm not saying the .300 WSM isn't a good cartridge, or that hunters don't buy them now, but it's not the super-hot bestseller it was from 2001-2005.
So why are old 7mm RM's still showing up on used racks? One guess is that the rifles hunters bought during the peak of it's popularity might be losing some of their accuracy. The 7mm RM isn't kind to throats, and a rifle that was new in, say, 1978 might be finally losing its accuracy edge. I picked up a used tang-safety 7mm RM about 10 years ago for a very low price, just for the action, and my bore-scope showed the throat was gator-skin for several inches. Never did shoot that barrel to find out if the erosion affected the accuracy, but my guess (based on some experience) was that it did, at least somewhat.
Another guess would be that the guys who firmly believed the 7mm Remington Magnum was a "big cartridge" back in the 1970's finally realized it wasn't. Back then it was promoted as doing anything a .300 magnum would do, with .30-06 recoil. This was mostly because of the original 175-grain factory load's advertised velocity of 3020 fps. The first Remington ammo was right around there, but within a few years it was found the velocity was too much, and the factory velocity was dropped to around 2850, which isn't all that much more than the 180-grain .30-06 load.
Then, as others have pointed out, chronographs became affordable to average shooters. And eventually laser rangefinders showed up, providing some reality to long-range shots.
I knew Montana guys back in the 1960's and 70's who firmly believed in the ultra-power of the 7mm RM, who when anybody asked what cartridge they used for elk would roll their shoulders like a weight-lifter and say, "I shoot a Big Seven." These guys all had tales of 700-yard kills, which for some reason was the typical range quoted. Maybe it was because many of them preferred "7&7" as their mixed drink, and a 7mm Magnum at 700 yards matched that perfectly.
The 7mm Remington Magnum would actually a darn good choice for the guys who like to make long shots these days. After all, John Burns uses it a lot, and the typical 7mm rifling twist stabilizeslong 162-180 grain spritzer boattails. But unfortunately, the Big Seven doesn't fit in a short bolt action, and has a belt, and long-action belted magnums are just as unfashionable right now as they were fashionable half a century ago.
