I bought a High Standard 22 mag over/under derringer new in the early 70's. To load break open, it also cocks the gun. no safety, no trigger guard. Not really the gun you want in your front pocket. Ended up trading it off. Never shot it.
I bought a new in box Smith and Wesson 642, I brought it to the range fired three complete cylinders of standard pressure ammo. On the second shot of the fourth cylinder the internal lock engaged on its own rendering the gun unshootable. Figured it was a fluke so I unlocked it (I had the key with me) fired two more cylinders then on the last shot of the third it locked up again.
Needless to say I sent it back to S&W and had them replace it. As soon as I got it back I sold it. I personally will never own another S&W with a lock. If that would have happened in a life or death situation it could have gotten someone killed.