The Remington 600 family of rifles:
600; walnut stock, 18.5" barrel with vent rib and open sights. 222, 223, 243, 6mm, 6.5mm Rem Mag, 308, 35, 350 Rem Mag. The 223 and 6mm Montana were limited editions, very uncommon.
Succeeded by:
660; walnut stock with black forearm tip, 20" barrel with open sights. 222, 243, 6mm, 6.5mm Rem Mag, 308, and 350 Rem Mag.
Succeeded by:
600 Mohawk; birch stock, 18.5" barrel with open sights. 222, 243, 6mm, and 308. The barrel contour on the 600 Mohawk is heavier than the early 600. 600 Mohawks were a non-cataloged rifle that was only sold new through high volume retailers like K-Mart and J.C. Penney.
There may be some end of the run 600 Mohawks that were made with leftover 600 stock and 660 stocks and barrels. I have heard of them, but have never personally seen any.
JEff
