I live in Ohio and with the cold weather coming on I was trying to figure out what is suggested when you go from a 20 deg outside setting to a 70 deg building and your optics fog.  The flip up backup sights that are co-witnessing with the optic do not help. Or if the optic took a hard hit and you can not see through it due to broken glass or internals then what? And in a pressure situation you would not have time to remove to optic.  I am trying to set up a m4 gery and have no experience besides hunting with standard scopes.  Thank you for any reply.

With your Aimpoint mounted on an ARMS #22M68 it takes less than 2 seconds to remove the whole sight and mount (and I'm being generous as I suspect I can do this much faster), I'd be more concerned about my glasses fogging up than my optic. As my BUIS is generally always in the up position IRL situations IMO I don't see this as a big concern.

Mike

Realize you do not need optics. Your eye & brain have a "couple" of years evolution, trust them.
GG

Uhhh, fix bayonets? Sorry, had to be a smartass.
I've never thought about this, good question.

My thoughts exactly.  It takes longer to change mags than it does to change your optic if you have QD capability.

Bradd

Look at some Israeli weapons.

Make yourself a para-cord retention system.
1 end to the optic, 1 end to somewhere on the upper, like the delta ring.

That way if you have to dump the optic you won't have to worry about dropping it or retention.

Thanks for the input.  Trying to learn before I buy.  

Worst cases scenario, run a stick through the glass to get it out of the way. A $400 optic isn't worth dying over.

Training should reveal these issues to you, and allow you to develop solutions ahead of time.

Go back to Tactical Carbine 101. What do you do ANY time your carbine is "downed?" Transition to your sidearm. Drill this over and over until it becomes second nature. When weapon #1 doesn't work, go to #2. Your fastest route back into the fight is to produce another weapon.

Personally, I haven't had any issues with my EOTech fogging, although indoor and outdoor temps around here don't usually include 50 degree differentials. I see what you are driving at; you aren't talking about going to the range, but talking about doing an entry into a residence. While I haven't encountered optical fogging in those situations, my eye protection really likes to fog up, and anti-fogging compounds haven't helped a bit. The best solution I have found for that is to buy cheap safety glasses, don't use any retention cord (tends to get mired under chinstraps and boom mikes) and ditch them if they get obscured. That way, if they get stepped on or otherwise taken out, you (or whoever issued them to you) are only out a few bucks. We basically treat them as an "expendable" item.

Consider also the possibilty of rain pooling on the glass.

Some surplus stores sell anti fog cloths that are used to clean the lenses in gas masks. These things work GREAT.  One should keep in mind that the lens will occasionally have to be re treated.

Note that there [i]may[/i] be some change of zero for the irons when you remove a cowitnessed dot sight.  Check it out beforehand.

I had a Leupold fog up on me a couple of years ago when I was stalking an elk.  I had quick detach rings, but no iron sights!  Luckily the elk waited around for me to get my scope cleared up.

Probably the ONLY advantage to the carry handle mounts is that most of them have a sight channel that allows you to use your irons without looking through the optic. Disadvantage is that they are clunky, and your optic is more likely to get pranged.
Q