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Bad holes?

fltopsvetfltopsvet Member Posts: 7 ✭✭
edited May 2009 in Ask the Experts
I am curently building my own M4, have noticed a problem. When I have the bolt assembly in the upper, front pivot pin secured, and attempt to push in the take-down pin, it wont go in at all. The pin will go in either hole when the lower and upper are seperated, but together its a no-go. Any idea's?
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    sandwarriorsandwarrior Member Posts: 5,453 ✭✭✭
    edited November -1
    How do you get it to go in the rear hole and not the front? If you put the pin in the rear hole what does the alignment look like in the front hole? You may need to have one or the other hole reamed and the upper shimmed to the lower somehow. I'm not sure if the accu-wedge will take care of your issue but that is what I understand it does. Keeping the upper and lower tight so your point of aim never changes from your cheek weld position.
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    fltopsvetfltopsvet Member Posts: 7 ✭✭
    edited November -1
    Sorry if I mixed you up. The Front pin IS the one already in place, the rear has issues going in after the front is already in. The front pin is the pivot pin (barrel end of the upper), the takedown pin in the rear pin (Butt stock end)
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    sandwarriorsandwarrior Member Posts: 5,453 ✭✭✭
    edited November -1
    Front or rear, whichever pin is in (as per your first post) what do the hole look like when the upper and lower are aligned ready to be pinned together. It doesn't take but a few thousandths for one hole to be out of line and they won't both pin. What to look for is which pins and leaves the upper closest to the lower in the rear. Meaning which leaves the smallest gap between the back of the upper and the forward part of where the buffer spring goes in.
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