Originally Posted by streetglideok

A 280 Remington, aka 7mm Express, is a necked down 30'06. A 7mm Remington magnum, is a step up in powder capacity, and ballistics. I'm not sure where you would get that its a step down.
Federal Ammunition Load# 7RA 150gr powerpoint, MV 3110 FPS, 3221 Ft-Lbs of energy.
The same bullet, in a 280 Remington, Load#280B is 2890FPS, 2782Ft-Lbs energy.

Ok, lets drop to 140gr, 3150FPS for the 7mm mag, and 2900 for the 280.

In 160gr, the 7mm mag, 2950FPS, the 280, well Federal doesn't offer that weight. I went to Hodgdon Powder's website, and the best data they have for 160gr slugs, is a full 200FPS less, then the 7mm Mag.

So in closing, the numbers speak for themselves. It holds more powder, a little less efficient, pushes bullets out 200fps faster, and, though the 280 is a great round in my opinion, the 7mm rem mag is alot more popular and easier to find ammo for.