Mike:  The Redfield 102k is a convenient sight.  If the coin-slotted screw is loosened, the elevation slide can be raised to allow bolt removal.  The set-screw, if adjusted properly, allows return to the previous elevation setting.  The elevation and windage screws hold their adjustments well.  The flat piece of sheet metal is a cover and indicator.  It covers the elevation slot and indexes the elevation increments.  It is often put on wrong (i.e. underneath the slide instead of on top).  A recommendation on later Redfield instructions is to put a magazine cut-off shaft (with the lever removed) in the cut-off opening.  There is a roughness in cartridge feeding if nothing is in the slot machined in the receiver for the magazine cut-off.

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