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Posted: 12/9/2016 6:08:09 PM EDT
| I have had Eotech and aimpoint T-1 in the past . recently I got back into the AR platform and I am on a learning curve again. here is my dilemma.. I have a Aimpoint PRO mounted on a PSA Freedom upper(mid length gas Dissipator) with F marked FSB, I am currently using a MBUS as a rear flip-up. here is my problem... I sighted in at 25 yards with the aimpoint, no issues.. then I flipped the rear MBUS to adjust that.. I already knew the Aimpoint does not co witness, but looking through the MBUS with the aimpoint "on" my dot is halfway down the front sight... so I took my aimpoint off and lined up the MBUS and FS post... I'm shooting almost 4" higher with the back up sights..no hight adjust on the MBUS, and I can't believe I would have to move the front post that much... I took the spacer out of the aimpoint and re-zeroed that but all that did was drop my dot farther into the FSB????? WTF? I never had issues with my 512. it co witnessed with the BUIS just fine... soooo... is it the aimpoint? the MBUS? or me? I'm pretty frustrated at this point...thanks! |
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Why do you "know" that an Aimpoint Pro will not cowitness with iron sights, including a FSB and Magpul MBUS rear?
It should be able to cowitness at lower 1/3 height, with the dot centered in the field of view, and the front and rear sights aligned with each other down in the lower 1/3 of the field of view. If you look through the iron sights, the dot should still be right over the front sight post, or close to it. 
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just from what I have read... alot of posts saying it's not an absolute co-witness and it's not a 1/3 it somewhere in between. all I know is I shot at 25 yards and zeroed the aimpoint no problem, never really bothered to see where the dot was on the FSB as I shoot with two eyes open... I then flipped the MBUS and the dot was halfway down the FS post... it's all just confusing to me, last AR I had I put the Eotech on and the dot sat right on the tip of the front sight even when looking through the flip up rear.
ETA: my sight picture looked like the far right except the dot was not on the tip of the FS post it was on the bottom... does this mean I have to adjust my FSpost down that far? after all the aimpoint was hitting right on at 25 yards |
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Quoted:
just from what I have read... alot of posts saying it's not an absolute co-witness and it's not a 1/3 it somewhere in between. all I know is I shot at 25 yards and zeroed the aimpoint no problem, never really bothered to see where the dot was on the FSB as I shoot with two eyes open... I then flipped the MBUS and the dot was halfway down the FS post... it's all just confusing to me, last AR I had I put the Eotech on and the dot sat right on the tip of the front sight even when looking through the flip up rear. That would be absolute co-witness. That may be what you are used to. There may be an absolute co-witness aftermarket mount for the PRO, I just don't know. Lower 1/3 (or similar) does work well for most people. You must sight your iron sights in independently of the red dot, and sight the red dot in independently of the iron sights. Once those are each done, separately, regardless of the co-witness height, if you look through the iron sights, you should see the dot right above the front sight post, but if you just look through the red dot field of view, the iron sights will be well down below the dot, giving you a more clear field of view. |
| thanks for the help.. I did in fact sight them both , with the rifle benched and I took the aimpoint off.. it shot quite high at 25 yards with the irons . which would mean I have to move the FS post up? correct? maybe I'll get a better BUIS and a mount that is for absolute ... thanks... |
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Yes, raise the front sight post will cause the shots to move down, it points the barrel down. The problem is not the MBUS. I have one on my carbine and it works just find with a F marked carbine gas block A2 FSB.
Do you have a photo of the setup, especially the front sight? |
| When you say " it shot quite high at 25 yds", how much are we talking? Because if irons are zeroed for 100 yds they WILL be high at 25. You need to zero them for the expected ranges you are shooting them. And you have been told correctly that irons and red dots are zeroed independently. |
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