I have several newer Smith revolvers with the lock. I've always been skeptical about reports of the locks self-engaging, until this afternoon. I began shooting my 632. On what would have been the 5th shot the gun locked up. I've read that this occurrence is most likely with lightweight revolvers using hot loads. Though I've owned this gun since 2012, it has been fired very little, and never with magnum ammunition. Today I was shooting "powder puff" loads of 1.5gr Bullseye with a 90 gr. cast bullet in .32 acp cases. It is a fairly easy proceedure to remove the locks--there are several youtube videos that walk you through the process. I would strongly advise anyone carrying a Smith revolver with the internal lock to remove it.
THIS CAN AND DOES HAPPEN!
THIS CAN AND DOES HAPPEN!