Got this from another board: Figured it out, the secret is you have to remove the magazine tube about an inch or so and of course it is stuck and fragile. I used an old 577/450 case which was floating around my reloading bench, drilled and tapped the end for 8-32 threads, (same as your cleaning rods) cut a long screw so I had a treaded stud, locked it down with a nut. tapped it into the end of the brass tube and used a small hose clamp to lock the tube to the case. Hooked a cleaning handle and puilled, slid out
like a charm. Receiver out and ready to clean..
It worked !