Raimey;
I stand at attention any time I hear Dixie being played. A few weeks from now my SCV camp & my Wife's UDC chapter will be joining in a memorial at the Confederate Cemetery in Tullahoma TN.
The Sauer is a sidelock Knock-About grade made for VL&D CA 1902. The Clabrough I believe to be from the 1890's. Both are as I said double underbolted with a plain unbolted Doll's Head. Neither have any form of wear compensation, yet both remain tight. Both are 12ga. Both have back action locks but with plates that look like a bar action.
The Lefever is CA 1889 & has a vertical set bolt with a hook at the top. This hook engages the notched Doll's Head from the rear. For opening its top is rocked back by the side pivoted top lever. It has a screw through the top tang in front of the lever which bears upon the top of the bolt which can be turned down to compensate for bolt wear. On all three the lever simply comes to center & stops, always has, always will.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra