Remington designed the XP-100 to be a pistol from the start. It is illegal to make a handgun from a rifle, but it is OK to make a rifle from a handgun. (stupid federal BS!) The Remington XP-100 action was thought to be useable as a short action rifle, so with some modifications, it became the Remington 600. Then the 660, and finally the 600 Mohawk. I believe the model 7's action is somewhat different with more of the model 700 features than the 600's.
Paul B.