I call that a quill, and it is not the base pin or stud which is the very center of the star for me. Part 885a on your schematic in post 12 as previously discussed. Others have called it a base pin and I recall that my Navy Arms schematic calls it the same. Your schematic calls it a extractor stud and 2152HQ calls it something else, but we are talking about the thing that limits the rearward travel of the cylinder. The point of measuring the gap when the cylinder is open is he furthest back the cylinder can travel. It the gap when the gun is closed is less than when it is open, the cylinder should not be able to contact the tabs, BUT it is somehow doing that very thing??

For some reason, it looks like the area around the center hole is chewed up? I wonder if the pin or stud is not seating all the way in and might be resting on the edge of the hole until shot? This is a true mystery still.

__________________
Gary
SWCA 2515