Thanks to modern technology, I have been able to talk about several weapon lights (such as the Crimson Trace Lightguard) that are small enough that they can fit on concealed-carry handguns. The same thing can be said about red dot sights.
Mini red dot sights have been around for well over a decade, and there are now so many of them out there it's hard to keep track. Just off the top of my head I can think of the Burris FastFire, the Docter, Bushnell First Strike, JP Rifles' JPoint, Insight Technologies' MRDS, Leupold DeltaPoint and the Trijicon RMR.
Competitive shooters have been using red dot sights on handguns for 20 years, and it was in part the competitive abuses of larger red dot sighs such as the Aimpoint and EOTech that resulted in them getting tough enough to get approved for military use. Mini red dot sights are a more recent phenomenon, but they are not delicate little toys anymore.
Mini red dot sights are popular with the current 3-Gun crowd as secondary sighting systems for their AR-15s, faster to use than traditional iron sights—especially in close-range engagements. Trijicon has been selling its popular 4X ACOG riflescope with a mini red dot perched atop it for years for just this sort of situation.
As durable as they were, however, it has only been the past few years that the idea of putting mini red dots on carry guns has taken off. In large part this has to do with the introduction of the Trijicon RMR (Ruggedized Miniature Reflex). Trijicon is not known for making delicate, maintenance-intensive products, and when it not just introduced a mini red dot but recommended mounting them on pistols, many tactical types sat up and finally took notice.
Gabe Suarez, a well-known tactical trainer who has taught at Gunsite, is now advocating (and selling) Glocks, SIGs and Smith & Wesson M&Ps with slide-mounted Trijicon RMRs. I've tested a lot of these mini red dots, and while most of them are very well made and durable, I haven't seen one that can compete with the "pound a nail into wood" durability of the Trijicon RMR.
The fact that Smith & Wesson is introducing a series of pistols that have removable plates on their slides for built-in mounting of mini red dots should tell you these optics are here to stay. The technology will only improve. I predict we'll see true holographic (screen- and tube-less) red dot sights within 20 years.
There are two advantages to a red dot sight. The first is that they are easier to see if you have less than youthful eyes. I know plenty of shooters who just can't see the front sight anymore beyond a blur. A red dot is on the same focal plane as the target, and as long as you can see the target, the dot will be in focus as well.
The second advantage is perhaps the least important: They are faster to use. Instead of lining up the front sight with the rear sight with the target, a shooter has only to place the dot on the target and pull the trigger.
How could speed be less important than visibility? Several reasons. First, while red dot sights are inherently quicker to use than iron sights, that speed difference will only really be noticed in the competition world where you're firing dozens of shots at multiple targets.
An experienced competition shooter will be hundredths of a second faster from shot to shot using a red dot, and that time can add up over the length of a match. In an actual self-defense shooting situation, it really is a non-factor.
Second, if you haven't practiced enough with your red dot-sighted pistol, it may actually be slower to use than one with traditional iron sights. Grab about any pistol and look down the slide. Sights or not, you've got a pretty good idea where it's pointed.
The body of a red dot sight tends to obscure the slide, and I've seen plenty of shooters new to their red-dots wiggling them around in their hands, trying to find the dot in the little window.
When you fire that little dot jumps up and you completely lose it in the window. Finding it again as the pistol comes down out of recoil can take some time if you're not used to doing it.
The best solution is a red dot-sighted pistol equipped with iron sights tall enough to be used through the window of the red dot. The eye sees the iron sights as you bring the pistol up on target, and as they more or less line up the red dot is right there. They tend to draw the eyes to the dot, giving you the best of both worlds.
That is exactly the reason the iron sights supplied on the FNX-45 Tactical are so tall. These tall sights were originally designed to be used with suppressors, but they work great with mini red dots as well.
If you're having a hard time seeing the sights, or want to try something completely new, look into a slide-mounted mini red dot sight for your pistol.
Mini red dot sights such as the Trijicon RMR are rugged optics that place a sighting dot on the same plane as the target, eliminating the need for aligning front and rear sights with the target.