If you go to the Aguila Ammo websitewww.aguilaammo.com/minishells.htmThey explain the use of the shell. It lists a few pumps that can handle the shell and they mention modifications to other pump gun so they can use the shell. They also state that autoloaders are out of luck.The following page explains the shells use in a pump gun (with comments on the MOSSBERGS 500/590s and REMINGTONS 870s):www.aguilaammo.com/minish...n_mods.htm Let the dog hunt the birds, ... you hunt the dog.Edited by: GordonSetter at: 11/14/02 9:20:01 am