I have a pair of Cobra derringers in 9mm that I got cheap. I had to tune both extractors for decent reloading.
What I didn't like was the clunky manual safety. Absolutely vital, but VERY slow.

I redesigned the safety buttons to be spring loaded so they clicked off automatically when the hammer is cocked (I got the idea from an old Hawes 22 mag derringer).
In my mind, they are no longer bashing fodder.
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I don't have Alzheimer's- My wife had me tested.