...The action is modelled after the XR100 pistol action.
They are hooked up pretty well. 70s might have been the highmark for the quality of Remington hookup and that might tick off swampy but there you are. Big Green has lost a step in the 1980s. When people doubt this I just say either 710 or ask them to take one of those modern sps in a RUM and ask them to check out the play in the bolt and the action.
Sincerely,
Thomas
IIRC, the 600/660 came before the XP100...
and i have both M600 (.350 RM)and SPS RUM (.375 RUM), and the SPS has no more bolt slop than the 600. sorry, but reality.