Remington 700, Savage Small Shank
A Remington 700 fit barrel is threaded 1-1/16×16 TPI and has a bolt face recess. It will fit factory Remington 700 actions and custom actions that match this aspect of the Remington design such as Defiance, Surgeon, Stiller, and others.
A Savage Small Shank barrel is threaded 1-1/16×20 TPI and has a flat face. It will fit custom actions that match this thread pitch, such as the Black Collar Arms Pork Sword Action, Bighorn, Shilen, APR G2, American Rifle Company, Ultimatum, and others.