The brass on the shell has a belt, like a belted magnum rifle round (think Weatherby). These belts can be lathed off and the shell used to reload for 8 gauge guns so I have read on more than one occasion.
Usually swaged in a die or just peeled off.
These are called 'Kiln Guns'.
A customer of mine used them heavily (Ashgrove Cement) and one of the employees collected the hulls for me. I have given thousands of the things to 8ga shooters who post here.
This is a good link to see how they are used:
http://alboayz.com/english/projects.htmlYou will also see them in coal fired generating stations to clear buildup of hardened ash in the exhaust of the boilers.