Well, "IF" a 280 Rem can be safely fired in a 7mm Rem Mag rifle, that would leave one to think the opposite would be true???
Try to chamber a 7mm Rem Mag in a 280 and see how far you get.
If you were talking to a lady at Rem, I am sure there is a misunderstanding. Perhaps she ment both the 7mm Rem Mag and 280 Rem are chambered in the same style rifle. Or as mentioned, shoot the same caliber bullet.
This is certainly not something that should ever be tried, EVER!!!
Kirby Allen(50)