Just before forcing cone there is a sharp edge that collects lead when shooting cast bullets. What can be done to prevent this lead build up ?
Using my bore scope i examined the cylinders of my 686 against my Blackhawk. The 686 has a sharp edge before forcing cone with a gap of about .020" between case mouth and chambers sharp edge. Maybe this sharp edge is shaving lead? The Blackhawk has no sharp edge with smoother transition. I never noticed leading in this area of Blackhawk cylinder.
Here is diagram i tried to draw. Maybe our 686 guns need to be sent back to S&W to be modified to shoot cast.