The pictures that Driftwood Johnson posted are extremely helpful in understanding exactly how the lock works. When engaged, the "flag" rotates up and back and the small tab on the "flag" engages a slot in the hammer thus preventing it from moving. Once you understand how the lock works, it makes many of the so-called reports of it self-engaging very suspect. You see, in addition to the lock "flag" being held down under spring pressure unless manually engaged, it is also held down by inertia when the gun recoils. Likewise, the slot in the the hammer that the "flag" tab engages in only aligned when the action is at rest. When the hammer is fully forward against the firing pin, as it would be when the revolver is fired, the "flag" is blocked from moving up into engagement by the hammer itself.
Therefore, in my estimation, if the lock were to render a revolver inoperable without being manually engaged, it would almost certainly be due to defective (i.e. broken) parts, grossly out-of-spec parts, or parts which were installed improperly. As such, a genuine "auto lock" (as opposed to a different problem which is mistakenly blamed on the lock) would almost certainly be a quality-control issue rather than a design issue. While there are many unverified reports of "auto-lock" (as in anonymous internet posts), when one starts looking into the details of these reports they usually either don't support the claim of "auto lock" or are missing all together. I am of the opinion that the lock, at worst, represents no greater detriment to the overall reliability of a S&W revolver than any other QC issue.
Now, I can understand why some might dislike the lock because of the aesthetics of it or because of the politics they feel it represents. Those are matters of personal opinion and there's really no point in trying to debate it. However, the contention that the lock represents a significant detriment to the reliability of the gun is, at best, poorly supported. Given the emotional response of some of the lock detractors (such as the use of childish invectives like "Hillary Hole," "Smith & Clinton," or "Safety Wesson") when their claims are challenged, I suspect that a great many of these claims are based in an attempt to justify personal opinion rather than fact.
