I hate to admit it, but I have 4 guns with the damnable lock. A 642-2, a 442-2, a 25-13 mountain gun, and a 625-9 mountain gun. All were bought new. On the advice of my gunsmith, who is an S&W specialist, I have NEVER activated the locks to the locked position. He says to just leave them alone and there should be no trouble with any self-activation problems. But being a belt and suspenders kind of guy - just in case - I carry a lock key on my key ring. Not to lock the gun, but to unlock it, again, just in case. I see Smith is now making some 642s without the lock; I wish they were doing that when I bought mine about a year ago.