+1
My 870 came with the "tactical choke tube" but I think that's mainly for mushroom stamping hippies. Don't think it would work great on a lock since it's meant to jam into the surface of a door but would love to see what a slug would do!
Here's some research for you: http://www.theboxotruth.com/docs/bot5.htm
Everyone wants to be a frogman on Friday
You can't beat a woman who shoots - RW Swainson