I recently bought a new 642 airweight and have experienced occasional problems with it firing. Every once in a while I can pull the trigger all the way back and there is no hammer fall. Mine is the fully enclosed hammer model, so I can't see it and am assuming the sear is not releasing and the hammer not falling.
Each time I opened the cylinder to see what might be wrong and the revolver functioned after reclosing the cylinder. I later noticed when dry firing that sometimes there was a very slight delay between pulling the trigger all the way back and the hammer falling.
I thought it might be the internal lock, which I had never touched before. I turned it on and off a few times and then torqued it down tight in the unlocked position. About 50 rounds later I had not had another malfunction and dry firing does not repeat the ealier problem.
I am wondering if maybe the recoil slightly engages the internal lock sometimes, but I am just guessing.
Is this the internal lock problem I have heard people refer to or is it something more serious?
Any comments would be appreciated.