I always thought that it was introduced in the late 50s as a .280 and was changed to 7mm express in the early 70s, then back again.
Yes, that is how I remember it happening also.
It's interesting to hear all the theories on why the .280 would not be selling, especially the ones that say that it isn't selling because of the strong competition from the .270, 30-06 and 7mm rem mag. If this was true, why would any of the slew of new cartridges developed in more recent years sell at all? The truth is that they probably don't either. A good many have already bit the dust in only a few short years mainly because they don't perform any better than the old reliable cartridges. I can see the gun manufacturers making guns in only the well known standard calibers in the future. I just don't think it's cost effective for them to bring out new calibers. Sure some of the gun nuts will want to buy them, but in general I just don't think there are enough of these people left out there to really make a substantial improvement in a gun companies earnings.