I had a derringer and they are to short, and usually the mechanisms are to rough and usually they are to small to handle safely imho, my right hand ran into a derringer I was handling and it went off, the bullet went thru my right hand and 20,000 dollars later and a good surgeon, my hand is ok thank the Lord.
I still have pistols, but all barrels are 4 inch or longer, no more accidents..............it was my fault it went off, but never again will I own a derringer, you are asking for it imho, way to small for safe handling.