I have a Davies derringer in .22lr.
A lot of fun - but - that's about it as far as being useable for anything.
I did used to carry it in my jacket pocket loaded w/shot shells when I mowed the yard the first few times each Spring though.
The grass that time of year grows real thick real fast & the snakes could hide in it.
Every once in a while one would get caught in the blades and come out alll mangled but still alive. A shot to the head put it out of it's misery.
As far as being any use for SD - you'll have to judge that for yourself.