Short history lesson, from a personal point of view...
Several posters got it basically right, but either didn't know, or left out some important details. In a nutshell, here's why some models have locks, and some don't.
Thank the Clinton administration, some British gentlemen, Safe-t-Lock, and of course, all the usual suspects in the anti gun movement.
As was said, back during the Clinton administration, several big city mayors (with the administration's tacit approval) were pushing to sue gun makers, supposedly to recover some of the "expense" from gun violence in their cities. This was a very real threat to the industry, because unlike their media image of giant coporations with huge profits and bottomless pockets, the reality is even the biggest names in US gun manufacture are not really large companies. Their profits are not what the media makes them out to be. So, even if eventually found blameless, the cost of defending themselves in court, constantly, for who knew how long, could be ruinous.
And, really, thats what the big city mayors and other anti gunners wanted all a long. Now along comes the Clinton administration's "voluntary agreement". This is full of promises (many of which which are lies), and a host of "safety improvements" (restictions) covering gun manufacture and sales policy.
Some of these (but by no means all) were built in locks, loaded chamber indicators, serial # in hidden locations, etc. for all new models and where possible, redesign to include them in all models. Among the sales restrictions was language to prohibit anyone under 21 from being in the part of the store where handguns were sold. And, of course penalties like prohibiting a maker from doing business with a dealer who did not follow the new restrictions, etc. There was a lot more, but I think you get the drift.
Now, what they offered gun makers for complying with this "voluntary agreement" was protection from the lawsuits being sought by the mayors, and (in the case of S&W) preferential treatment in future Federal arms contracts (something they could not legally do, in short, a LIE)
Enter the "British gentleman". At this time, S&W was owned by a British holding company (Tompkins LTD, IIRC), and they decided the best thing for their business was to accept the Clinton's agreement.
The people working at S&W didn't have any choice. Their owners agreent to it, and they were stuck. So they set about designing locks into some models of the guns, and hoping for the best.
What happened then wasn't the "best" but it could have been worse. US, we, the S&W gun buying public went, well...ballistic. S&W was the only US gunmaker to enter into the Clinton's BS agreement. We saw it as a betrayal, and reacted accordingly. S&W sales fell. We talked boycott (and did it) in every way we could. S&W stock tanked, and the British owners wound up selling S&W for a loss!
Now, note that other US gun makers began putting the "Clinton approved features" in some of their guns (like Ruger did in its Mk III .22 pistol), but they never joined the "agreement", they just did it as a marketing stategy. By not joining the Clinton's agreement, the buying public didn't see them as betraying our rights, and they didn't get boycotted.
S&W get bought by the company that invented the lock, so, naturally, they keep the lock in those models. Over time, our attitude softens, and we go back to buying S&Ws (general buying public, I still know a lot of people, myself included, that won't buy a S&W with a lock) their stock comes back a bit, and S&W marches on.
Guns like the M&P auto, their 1911 and some others don't have locks because either they weren't in production at the time, or S&W didn't get around to putting locks in them, when there were under orders to do so. Adding a lock to a gun design costs money. So does removing it. With the economy and sales being what they are, all companies tend to avoid doing things that cost them money that they don't absolutely need to spend.
We are seeing some "new" models being made with without locks. New designs (autos mostly) may have a lock, but its not a freakin' IN YOUR FACE hole in the side of a revolver that for generations before never had one there.
They don't scream out "Hey, look!, I'm PC!", or "I'll do what ever the anti gunners want, as long as they let me sell some of my products":barf:
Locks on guns are a stupid, useless, feel good solution to a non existant problem, forced on us by the nanny state mentality. Locks on unloaded guns serve no purpose at all, except possibly keeping you from loading and using a gun when you need it desperately, and don't have the key available. Locks on loaded guns are just flat dangerous (if external, like a trigger lock), and pose a potential risk of rendering the gun inoperable when you need it, for internal ones. The solution is, and always has been, lock the gun up in something (if you have a concern). Do the same with the ammo.
The emotional argument of a child getting your gun and shooting themself or someone else by accident cannot, will not, and does not happen if you lock up the gun and/or lock up the ammuntion in secure storage.
But because many people simply do not follow these basic safety precautions, we get force fed internal locks. S&W chose the stupidest manner possible for its lock placement. It was guaranteed to upset us as much as could be. Other makers now include locks on some of their models, but they are discreet.
Looking back on it, putting the lock "in your face" might actually have been a smart move for S&W, a gamble, but one they managed to survive. It upset us enough to nearly drive them out of business, but, it got them out from under British ownership, and with the rest of the gun industry seeing what we did to S&W for joining the Clinton agreement, it made sure that even if they had been considering it, they were not going to!
I think, over time, we will see more models without locks (revolvers, anyway), because that is what most of the buying public wants. If you want a lock in your gun, they will sell you one. IF you don't, (eventually, I believe) they will sell you one of those, too. As long as the govt doesn't meddle (again), I think eventually this will happen. When it does, I'll go back to buying new S&W revolvers. Till then, I'll buy the older ones, that I can count on. Its a personal thing, but hey, evey gun I buy is a personal thing!
I got one of the Rugers (new Vaquero) with a lock. No issues with it. Can't see it, won't EVER use it, I just pretend its not there. Can't do that with a S&W with a keyhole in the side of it!
