As far as chambering the Weatherby ammo into the Remington chamber, it was so easy I couldn't believe it...it fed easily and then the bolt closed with no discernable difficulty...I'm sure that's another reason why it went unnoticed for so long. The guy he bought the rifle from--a civil engineer, no less (nothing against engineers, I just woulda thought the "devil in the details" would've caught on earlier--the guy even has an FFL!)--told him specifically to "make sure you only put Weatherby ammo in this...", or something to that effect...moreover, last year, I helped drag a deer out that he'd shot with the darn gun, using that same box of Weatherby ammo...at the time, I didn't pay attention to what he was shooting. So yeah, it is very easy--with this particular rifle, anyway--to chamber 7mm Weatherby Mag ammo in a 7mm Rem. Mag chamber. And it shot "relatively" well, I guess. Anyway, we've changed his ammo, and he's appropriately sheepish about the whole thing...I think it scared him a bit.