Original "Express sights" were first used on rifles carried by hunting guides who had to stop a big ugly pissed charging animal FAST at close range because their client screwed up. So long-range wasn't a factor but extreme speed of sight picture alignment most definately WAS.
An "Express Sight" consists of a front dot (originally a tiny piece of ivory, today more likely to be Tritium
) and a broad shallow "V" rear sight.
The company most responsible for a modern resurgance in the concept for defensive handguns is Ashley Outdoors:
http://www.ashleyoutdoors.com/
NAA offers the Ashley setup as an option for their Guardian, and has a good pic of such a sight; note that it'll work even better with a bigger rear sight for a bigger gun but the idea is the same:
(From the NAA website:
http://www.naaminis.com )
As you can see, Ashley includes that "line" in the middle of the rear sight that allowed "target grade" shooting if desired, but mostly this is a "speed system" for close-range combat.
It has nothing to do with whether or not the sights are fixed or adjustable but because it's a "combat system", they're generally fixed.
Jim
