Ithaca5E and Old Joe are right about the stop screw on the Model 21. It does nothing to tighten up a loose gun or prolong the need for normal hinge or bolt maintenance at the time of high mileage looseness. The "silliness" of the Model 21 stop screw is that many owners, like Joe implies, screw the thing all the way in when the gun is young, and the bolt travel follows the screw into the slot to the end of travel in the next few hundred rounds, eliminating any further "adjustment" for the rest of the life of the gun. The correct use of the screw is to adjust it as far in as the bolt will allow without the first hint of sticking, assuming the gun is tightly locked shut at that adjustment. At the point where the bolt just starts to stick, Winchester recommends that the screw be backed out until it no longer sticks in the slot. On a fresh and new Model 21, this adjustment will allow many years of very minor adjustments of the screw to keep the gun crisp working and tightly locked. Although the reference to the stop screw as an adjustment screw may be a michaelmcintoshism, he is not the first to incorrectly describe the function of this feature.
