Ok, I am lazy so I'll just ask. I am planning a pre-ban flat-top M4 type build after 9/13 and I want to co-witness an aimpoint with flipups or a flipup with fixed front sight. What is the best approach wrt the mount and sights?
I have ben forced to the conclusion that individuals vary tremendously in how they sort out optical data. And that one set method of co-witnessing sights will not work for everyone. Perhaps somebody like Bartholomew Roberts who understands optics could explain why this is; although I suspect the reasons are as much psychological as they are optical.
In any event, it appears that any one individual will react to co-witnessing in one of three ways.
There are those guys who can instantly sort through almost any amount of optical clutter. They can have their front and rear iron sights right in the main sight plane of their red dot scope and never have a problem. In fact, they’ll tell you that they don’t even see the irons when they’re shooting under pressure. These guys have the best of all situations. They can go from scope to irons with effectively zero transition time.
Other guys cannot tolerate any optical interference in the scope picture without having to carefully orient each shot. Their only salvation lies in fold-down front and rear iron sights. Their transition time from scope to irons can get to be pretty lengthy, particularly when the clock is running or the bullets are flying.
The third group (the one I’m in) can operate well enough with a limited amount of extraneous stuff in the scope picture. We can either go conventional height on the scope; coupled with a fixed front and fold-down rear or in the alternative, fixed front and rear irons with the scope raised just enough to place the irons below the primary scope sight plane. This requires some transition time from scope to irons but, a lot less than the two-fold-down set up. (Side note: Not being able to get a proper cheek weld with a raised red-dot means jack squat. You have no need for a cheek weld with a zero parallax optic.)
The main thing to understand here is that nobody else’s opinion, mine included, means jack squat as to what will work best for you. The only way to know before committing to purchase/build is to beg, borrow or steal an example of each set up and try it.
My two 20" A2s have plain old Aimpoint carry handle mounts and QRPs like Chuck's. No problems with any of these. For my flatops, I have the ARMS Aimpoint mounts. I don't like the way the QRP uses that spacer ring to get the proper co-witnessing with irons. There was talk of them releasing a QRP that does not require a spacer. Does anyone know if that's available?
The irons in the sight picture do not bother me at all. My eyes are focusing on the target and the dot. It is only when I use magnified optics such as the ACOG that the blurred irons bother me.
One day I'll try the Larue. I like their products, but I'm in no rush as the ARMS works fine for me.