I Got my outside the belt holster for my Boberg from
www.elitesurvival.com
Size 2 Elite Deep Cover Ultra. I use one on my COP derringer too.
Adjustable snap to fit a lot of guns well.
If you go onto Boberg Web site there is a section to compatable rounds...quite a lot accually. Mostly has to do how well crimped the bullet is to the case.