re: Does anyone here have a Derringer?

I own 10 pistols. If I was just starting out I would buy a Sig 365 and 1000 rounds of cheap hardball 9mm Ammo. Go to a range and talk to shooters. Most will be happy to give you pointers. Shoot 100 rounds in 10 trips. You can then take lessons to become proficient with your gun. Then take CC classes.
A 365 comes with two 10 shot mags. But you can buy 12 shot and 15 shot sig factory mags. I have a 12 shot in my pistol and a 15 shot in my pocket. That’s 27+1 shots on hand. And the new 9 mm Ammo is what the FBI uses.
Good luck.