Currently have a bone stock Colt 6920 and am about ready to put an Aimpoint PRO on it…
Question is: will the mount supplied with the Aimpoint PRO allow me to use a Magpul rear backup sight and have both work with the standard front iron site? I want to be able to look through a magpul rear backup sight and have the red dot right in the center and sitting on the tip of the front post that came with the rifle. I understand this to be referred to as “cowitnessed”?
I have been searching and the way I understand everything, this seems to be the case but was hoping for a confirmation from someone.
I would say yes. My colt with matech buis co witness with FSB and standard AP pro mount. I’ve since swapped to a Laure mount but your setup should co witness.
My Pro using the stock mount, using my Daniel Defense fixed sights, fixed sight alignment ends up being in the lower 1/3 of the Pro…otherwise known as lower 1/3 cowitness. I have read countless online forum posts that say the Pro is absolute cowitness, but the one I have is simply not.
I have a 6920 with the Aimpoint QRP2 (the mount it comes with) and aMBUS Gen 2 rear backup sight. I would say my co-witness is somewhere in between absolute and lower 1/3. It honestly looks like a split between the two. That being said, I shoot both eyes open and don’t ever notice the front sight post.
The QRP mount that comes on the PRO is absolute co-witness with standard flat top upper and F FSB.
You can run your rear sight up or down, doesn’t matter to anyone but you, but absolute co-witness with irons up is gonna give you a cluttered up sight picture and you’ll wind up using your dot in the upper 1/3 of the optic.
I’d run the rear folded down or swap to a lower 1/3 mount.
I have that set up you’re questioning on a BCM. It’s exactly the way Hmac stated, they co-witness between absolute & lower 1/3 with the spacer installed. You can remove it & be closer to absolute but for me, that’s too cluttered.
Thanks, I think I will pick one up and see what happens. Everyone says this is the best optic at that price point so I suppose it is time to see what all the talk is about.
Just keep in-mind that the Aimpoint and the iron sights are two completely separate sighting systems that operate independant of one another and should be zeroed independant of each other.
Your goal should not be to have the dot sit perfectly on-top of the front sight post when looking thru the irons. While that may very well be exactly how they align after they are each zeroed individually, it is not something that you should obsess about
…then it’s common for the dot to rest atop the tip of the front sight post, when the shooter aligns the irons.
It is not a given that it will do so.
Between the sight, the mount, the receiver, the barrel, the FSB attached to the barrel OR the BUIS attached to a FF forend (particularly this; if the FSB is ever-so-slightly canted, or if the FF isn’t installed pristinely perfectly…), and the rear iron, there’s all kinds of tolerance-stacking and/or assembly gigs that can make the dot rest wherever…yet still where it needs to be to be co-witnessed properly with the irons.
It’ll be in the viscinity of the front sight tip, but where the dot specifically ends up is ultimately a matter of appearance.
If the gun prints as desired with either sight system, but the dot ain’t quite on the front sight post, the response should be something along the lines of “Huh, how about that…?”
I checked my zero for both the iron sights on my DDm4V1 and PRO about 3 times thinking they should line up. They do not, but are very close. I never really thought about the tolerances and slight height differences between the two systems, but it makes sense. One thing that does bother me is seem to be slightly more accurate at 100m with my RDS than my irons. I would have thought it would be the other way. I guess it could just be me though. That is why I like this place. Always something else to learn.
