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I don't have a 650, but I have the Square Deal and 550B, and have used someone else's 1050, and the Dillon measures are the same on all their units, AFAIK
. The only exception is for the presence or absence of the coil spring I mention below, which is not on the 1050 measure. I don't know whether it is on the 650 measure, but that won't affect setup.
The Dillon measures are slide bar measures. The case neck expander (where expansion is called for) is actually a combination steel powder drop tube and operating rod for the measure's charge bar. It pushes up to positively slide the charge bar cavity out from under the powder hopper and over the drop tube to dispense powder into the case. In the original Dillon design, the charge bar was returned to position to pick up the next charge only by a long wrap-around coil spring. That tended to fail to completely return the bar when powder dust got packed in the charge bar channel, causing partial or missing charges. So, they added a linkage rod that is pulled down at the end of the press's down stroke to force the charge bar to slide back into place and pick up a charge.
The linkage rod is threaded on the bottom end, and the threads are used to allow a nut and washer to adjust tension on a compression spring slipped onto the rod above them. That spring is what the lowering press ram actually pushes down on via a little extension that has a guide hole in it for the rod. The spring is then what actually pushes the rod down. Since dispensing the powder is inflexibly linked through the expander/drop tube/op-rod, they must use the spring to avoid a jamming conflict between the two charge bar moving actions (forward and back). The only adjustments are to position the measure on its threaded die adapter so the linkage rod drops straight down through the guide hole on the ram, and then to adjust the spring tension for positive return of the powder bar. The linkage rod has a bent tip on top and attaches to the measure through a hole in the charge bar return cam and is held there with a clip.
The charge bar is adjusted for powder charge by turning a hex screw on the end. There is an aftermarket micrometer adjuster available for it, too.