Yeah, I have seen one and I have seen the .350 Remington Magnum as well. The 6.5mm RM was brought out in 1966 and designed to offer .270 Winchester performance in a short action rifle. The problem wit h the 6.5mm RM is that the case is really too long to be used in a short action. It requires the relatively long .264 caliber bullets be seated deeply to fit into a 2.8" magazine box. Remington could only load up to 120g bullet in the cartridge due to the short action. 6.5mm cartridges are really best with 140g bullets. Compounding this problem was the 18 1/2” barreled Remington 600 carbine that had horrendous muzzle blast and ballistics that fell way short of the velocities Remington published with a 24” test barrel.

Remington finally chambered it in the 24” barreled M700 in 1971, but it was too late.
Now if you put this gun in a standard length (3.340" ) action with a 24" barrel, it would be sweet.