Remnard,

You're probably thinking of the original, laminated stock Model 600 (and I believe also the 660) which was offered in 6.5mm Remington Magnum. It was also offered in the non-magnum 6mm Remington.

I've run across Model 600/660s in a wide variety of calibers: .222, .223, .243, 6mm Rem., 6.5mm Rem Mag, .308, .35 Remington, and .350 Rem Mag.

The two magnums were typified by what was often described as "horrendous" muzzle blast from their 18-1/2 inch barrels. I'm always looking for a good, used .350 anyway.... I may never shoot it, but always wanted one.