These locks are a controversial issue & tend to get quite emotional in threads about 'em.
Many specious arguments are raised as to why they're no big deal, and truly they MAY not be a big deal for recreational shooters where a gun that locks itself up at the range is merely a nuisance.
There are, however, some facts to be considered.
One is that they undeniably add complexity to a very good design that is NOT improved in the slightest by their inclusion.
Another is that they DO fail.
While most individual users don't call the S&W Lock Failure Hotline, or their local TV news department, to report lock failures to be included in the national lock failure database; totally dismissing any account of a failure that you did not personally witness yourself is fatuous.
Another is that the percentages, as I noted earlier, ARE LOW, but THEY DO HAPPEN.
The odds are in your favor that your lock-equipped Smith revolver will never lock up on you.
But- there's always that small percentage that offsets those odds, and how can you guarantee you won't land among that group that falls on the wrong side of the odds?
With a lock, you're vulnerable to the laws of chance.
Without a lock, that particular vulnerability does not exist.
Another is the inference that these locks only seem to fail at the range, and never when actually needed, as when hunting or for self defense.
Consider, again, the percentages- a typical range session may involve anywhere from 50 to 200 rounds fired, whereas a hunt or defensive encounter may only involve one or two.
Where, again, do the odds of lock failure point you?
The range may be where the odds are greatest of a lock failure, due to sheer volume, but that in no way suggests that a failure won't happen after you've fired your first shot at a deer or attacker.
Also realize that most of these locked Smiths are not used for hunting, which further diminishes the possibility of a failure in the field.
And that in both of the cases we've been discussing, Bane's & Ayoob's, those happened to new guns.
As in the possibility of a first-occasion failure does exist, which is directly applicable to a buyer obtaining one for home defense & not shooting it much before it might be needed.
Arguments for & against a lock that nobody asked for & nobody needs, and which IS a bad design and which IS known to periodically fail, will continue as long as S&W continues to insist on using them.
The odds are in your favor, but if the lock's there, so does undeniably exist at least the possibility of failure, if not the probability.
We can bicker back & forth all day long, and there will be no consensus.
It boils down to this:
S&W took an unwanted position with these locks.
They are maintaining (for the most part) that position, in the face of strong customer dislike.
They are not admitting any fault with that lock.
They show no signs of backing down.
Many buyers today suffer from DK-DC Syndrome (Don't Know-Don't Care), until or unless they encounter a failure themselves.
Since the only new Smith revolvers offered (excepting a handful of Js) WILL have that lock, if you want new & it's gotta be a Smith then you have no choice, you're stuck with the lock.
You buy the horse, you also buy the horse manure that comes with it, and you deal with the downside.
We all have to make a choice- we play the odds & buy a new Smith with lock, or we don't.
Chances are we'll be fine if we do.
Understanding that somewhere, sometime, somehow, somebody WON'T be fine, and a failure WILL occur.
Whether that somebody is you, and whether it'll be at the range playing or in your hand fighting for your life, nobody can predict.
Once again, all of this has been an extended answer to the original poster's question.
Yes- the locks do fail.
Not often, but yes, they do.
Denis