I have personally re-set any number of police officer dovetail sights which became obviously off-center after a drop or, in one case, a really vigorous bump against a steering wheel.
In some cases, the friction fit is no longer adequate to really hold the rear sight in place. That little screw is insurance, and not really good insurance at that.
If you mash two pieces of metal together over and over again, eventually, everything gets out of spec. What you hope is that it is ONLY the sight and not the factory dovetail that gets out of spec. At least then, you do not have to replace the slide. How many times can you move your sight back and forth or take it in and out and still have a really tight fit?
Supposedly, SIG Sauer makes their steel sights softer than the slide so that only the sight deforms. Standard Glock sigts (polymer or steel) are the same. I do not know about S&W's sights, and I would not trust any answer on this subject that I might get from the current crop of customer service people.
Even more often, real shooters actually need to adjust the sights to hit to point of aim. Truthfully, however, only really good shooters need apply for precision sight adjustment. What I mean by this is that if you cannot hold a group, off hand, at 25 yards, that is the size of a saucer (or at least a paper plate), then you need more practice before you start hammering on your sights. Unfortunately, it seems to be that most people can barely keep their groups on a B27 at 7 yards these days. Sight adjustment is a completely futile exercise in such a case. More often, "the sights are off" is what someone says when what they mean to say is, "I cannot shoot worth a hoot."
Folks, you can make your gun shoot to the ten ring by just adjusting your point of aim. I know that is not ideal on a defense gun, but you are not going to convert a shooter with groups of 2 feet at 7 yards into a shooter who can keep them on a paper plate at 7 yards by "adjusting the sights" (or by installing new ones, for that matter). I have coached people before whose groups are so huge and so inconsistent at first that sight adjustment is the LAST of my concerns.
That said, good shooters need a good adjustable sight on a combat pistol.
After re-reading this thread, it is obvious that "what the world needs now" is a set of honest-to-God COMBAT sights that will hold point of impact when the pistol is thrown across the room into the opposite wall or which is bounced vigorously across a concrete floor. Those sights should NOT be fit with friction, and adjustment should be by a simple tool such as a screwdriver (please, not a hex key - I have never met one of those that a child could not strip out in really short order).
Yes, I know, there are plenty of adjustable sights, but those are more suited to the range than to combat. Don't believe me? Try throwing any pistol across a concrete floor or up against a wall if that pistol has Bo-Mars, or anything at all similar, and see what happens. Most of those adjustable units are held in the dovetail by friction, which means the whole unit moves even if the internal parts hold adjustment.
What I am thinking is a raised portion at the rear of the slide which is actually part of the slide itself so that rough handling does not knock anything loose.
This raised area, which would be the body of the rear sight would be part of the slide and protect the moving parts, which are easily user adjustable or replaceable with blades of various configurations, with tritium inserts, three dots, Von Stavenhagen "dot the i," etc., whatever the end user wants. Those parts so installed should be user replaceable as far as screws, blades, etc. to allow easy re-fit to a variety of options. All adjustments could be made at the rear sight by supplying, or making readily available through parts, rear sight blades of differing heights. Ever tried to get S&W to sell you its supposedly available different height front sights? Does ANYONE in the world have the chart that tells what increments they come in and approximately how much your group will move with each different height? Glock has such a chart readily available. They seem to be the only manufacturer that makes this information readily available.
The Bren Ten had a protected rear sight where the slide itself formed the "body" of the sight mechanism. Thus, its sights were exceedingly rugged. The worst part was the adjustment screws were tiny and imprecise (loosen one and tighten the opposite one). The front sight on the Bren Ten was also solid as a rock, yet finger replaceable by the end user.
If a slide re-design seems too radical for the gun company people, how about something MUCH simpler. On slides fitted with dovetails, how about a single hash mark on the sight and hash marks like a ruler etched into the slide - similar to those on the rear of the AR carry handle sights.
Wouldn't it be nice to see how far you moved that sight to the left or right when adjusting? Wouldn't it be nice to mark the little groove in the slide with some type of paint so you could always tell, at a glance, if your sights have moved?
This simple solution seems so obvious, it always makes me wonder if the people at factories who build guns actually ever shoot them.
Most of the gun companies are good about providing a bunch of stuff we don't need, and almost nothing of any practical value that we do need in new pistol design.
In my opinion, the lack of such obvious user-friendly and rugged features is holding back the M&P design.
Note to S&W: next time around, instead of trying to just be "as good as" Glock or SIG Sauer or Beretta, how about some really neat user friendly ideas that will truly set the design apart. Truthfully, interchangeable back straps and disassembly by the use of an on-board "tool" that no one can easily take out of the pistol are really not novel ideas. Nice, but please - no resting on your "laurels."
In the 60s, staked on sights sometimes flew off 1911 slides. Colt figured it out early with its exceedingly WIDE sight tenon, and their staked on sights just do not come off. They really know how to mount those. Novak came along, and as good as it is, dovetails are imprecise, subject to cutter variation and wear, and the actual sights are loose or tight based upon thousandths of an inch, which often is not controlled well in the manufacturing process. We have had no real improvements in the ruggedness of sights for far too long. You cannot fault Novak as he does not build slides, which is where the next step lies in this ongoing problem of the trade-off between ruggedness and end-user-friendliness.
I mean, really, it is ridiculous that every ten minutes someone starts a thread about being unable to move his sights on his M&P without a $100.00 tool, and even if you have one, the sights are mounted so tightly the tool won't work. I understand WHY they are tight, as too loose and the sights will not hold adjustment. But, just the other day, I read a thread about someone who sheared off a slide rail trying to move a sight with a sight tool. We are just beyond the "stone-age" and such foolishness is not necessary with proper design. And, with all due respect, making a too loose sight "fit" by peening is just a silly fix that is guaranteed to fail at just the wrong time.
Although just one idea, the attached schematic from the Bren Ten owner's manual will give an idea of how that pistol had its sight mechanism "built in" to a protected area that was part of the slide rather than an upright add-on.
Are you listening, S&W?