under what circumstances is this done? Is this when you have a stuck (unbroken) shell in the field? I've not had good result with this technique-- usually this just rips the edge of the shell off. I usually have to use a cleaning rod to tap out the stuck shell. How does one use the broken shell extactor device? BTW, I have a Plumcrazy lower-- it comes as a complete lower assembly-- the recoil tube is commercial spec aluminum. I built a piston AR with it for under $600. That area around the castle nut, with the upper in place, is as strong as on a aluminum piece.