Firearm top lever adjusting system

In a break open firearm having a frame attached to a stock, a barrel housing carrying at least one barrel and rotatable about a pivot on the frame at least one hammer pivotally mounted on the frame for movement from a cocked position to a position against the frame, a hammer spring urging the hammer forwardly, a firing pin aligned with each said hammer, trigger means operatively connected to actuate the hammer, a cocking rod mounted for reciprocation on the frame for acting on the hammer, and cam means for moving the cocking road rearward when the barrel housing is rotated about the frame, a fore-end housing and means for ejecting cartridges from the firearm, the improvement comprising a top lever pivotally mounted on the frame for opening the firearm, the top lever having an off-center cam projection which activates a locking bolt slideably positioned in the frame to engage a barrel assembly locking lug to move a locking bolt between locked and unlocked positions, the cam projection being positioned in an axial opening, and forward and rearward adjusting screws positioned to impinge on at least a portion of the cam projection to adjust the cam projection within the axial opening and the position of the top lever.