Hey keith44:
I have owned 2 derringers in 357.
Bought the first at the Triangle Gun Shop in 1966 0r67. It was a beautiful little gun but was not very accurate at about 15 feet, traded it. The next was a Buffalo Arms and it was too heavy and also inaccurate.
I decided that a snub nose would be better all the way around, light weight and more accurate as well as more rounds on board.
Something nostalgic about the derringer, love them old western movies, but for me, thats about all they offer, IMO just not a good defence or carry choice for me no matter the caliber. YMMV
HM