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Posted: 2/4/2009 10:01:59 PM EDT
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I'm building a disapator model AR. My FSB seems too tall. I can't get the post to go low enough to to get it zero'ed. I'm about 2-1/2" low at 25 yards with the post bottomed out.
I'm using a superior arms flat top upper with a Midwest Industries rear sight. The barrel is a government 20" barrel that I had turned down to 16-1/4". I'm using a rifle length Yankee Hill free floating hand guard. I've tried a GI FSB unmarked (no "F") A FSB on the hand guard rail, and the same FSB mounted on a 4 rail gas block. HELP!!!! |
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Are you sure the FSP is actually bottomed out?
I’ve encountered FSB’s that had bead blast material in the FSP well that prevented the FSP from completely bottoming out during adjustment. You might want to remove the FSP, then clean and inspect for contaminants. Lube, reassemble, then check the travel. |
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BTT for answers. My brothers DTI 16" has the same problem. He has YHM front and rear flip sights mounted on the flat top and free float rail respectively. Sighting the rifle in he is low about 2.5" at 50yrds and the front sight post has bottomed out. If anyone was wondering the front sight is rail height not a gas block height. I have done some searches on here in the past and have come up with zip.
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OK, the fsp is clean. If I remove the post completely, and use the FSB between the dog ears, I can come close to the right elevation.
I just tried a 3 rail gas block instead of the GI FSB. I attached the rail mounted site to it and it appears that I'll work. It just looks dorky. |
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I must not be explaining it clear enough.
On the front site base where the post screws into the base is about zero. It looks like this: )_( with the dog ears. If I leave the post out completely, and use the horizontal portion between the ears, it is about zero. What is the correct heighth of the sight base? |
| This may sound silly but are the sights for the carbine and the disapator the same piece? Obviously changing the distance between front and rear sights would change the height of the front or rear sight depending upon how you choose to look at it. My guess would be that the makers would make the sight with enough adjustment to be dual duty and cover both or all three models but had the thought crossed my mind. Maybe a spacer or taller rear sight. |
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