Originally Posted by
BehindBlueI's
During a real world event I was doing cover and move with a SWAT rifleman and (because Murphy) I flopped down right behind a car that happened to have been left running. Exhaust + below freezing temps instantly fogged my glass. I could still target focus and see a dot, I get the two eye superimposing thing. It wasn't fully occluded, but I get it.
Handguns, though, the back of the lens is what's exposed when it's riding in a holster. For concealed carry it's pretty unlikely to get fully occluded, I get that, but I have seen people drug around in mud, snow, etc. For a duty holster that's openly carried, debris (and climate dependent, ice/snow) becomes more of a realistic concern. If I have mud or snow packed in the lens, I've no redundant sighting system like I would with offset irons on a long gun. I've fallen in icy water during a search. I've rolled around on a muddy creek bank with a suspect. I've had a buddy drug backward in the mud by a dog to the point his holster was literally topped off with mud. Any of these events would have potential to completely occlude the side of the sight facing the shooter.
For those without the need for open carry, I fully get why it may not be much of a decision point. I get that and am not saying it's wrong. I was simply answering the question about decision points and "failure modes" that play into those decision points.