Actually the 7mm Rem Mag preceeded the 6.5 Rem Mag by a few years. I don' t really think it had much to do with the 6.5 not catching on. What it did do was pretty much push the 264 Win Mag into obsolescence. The 6.5 Rem Mag failed for the reasons GTBuzz mentioned, along with the fact that the 6.5mm bullet was never really popular with the masses and is just now being realized as an excellent caliber. The Remington 660 was just the wrong platform for the 6.5 Rem Mag. Can' t very well drive a Ferrari down a dirt road and expect maximum performance. Personally I think the Rem 660 would have been better off if chambered in the 358 Win. It is a true short action cartridge and has plenty of punch even with the short barrel. The Rem 600 in 308 was another good rifle for stand hunting or stalking through the undergrowth, but I guess that is a different topic.