Well at one time I had a HS 22 magnum derringer, the one that had a wallet , yep the one you could shoot through the wallet.
I shot it from time to time , probably never more that a dozen rds at a time. It broke twice. Ok as BluesBear said , light hammer strikes and the mainspring replaced.
I told the fella that wanted it , I was not comfortable with a gun that was not reliable to me. He wanted it anyway. I warned him about the problem in front of the gunsmith. Gunsmith concurred, the deal was done.
For .22lr...
Personally I have found the Win X22lr to be the most reliable ammo and across the board "accurate" in a variety of guns. Granted this ammo is readily available here. CCI Mini Mags and Stingers have been also ( when I find it). I don't do Rem ammo , rare if at all. Even tho an hour from me is a Rem ammo plant. Rem doesn't make their 22 ammo. As a kid I used the Rem "speedmaster" ammo and it was great...something happened.
Federal of all things in that 550 bulk pak has surprised me.