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Discussion Starter #1
Installing the rear sight on the M1A should be a task all of us can perform,, until recently..

Are others having issues trying to install the rear sights that can be turned with reasonable finger pressure? Recently, there have been four back to back installation attempts on new receivers, all failures.

The last one on the most popular brand of receiver was a three hour finger number. i could get the sight on but no left windage snap-back. Was unable to elevate without pliers... The covers, many were tried, produced far to much downward pressure, even when shortened.

Doing what should have been done first, I broke-out a dept mic.. The the sight base platform milled in the receiver was .024" higher than spec.. I took the spec reading off a halved TRW receiver. That out of spec figure may be the same one causing your issues.

Solution : "Kerrville Texas Solution", A GI rear sight base has a raised rib the runs across the front of base on the bottom.. you have probably notice this, also there is a depression on the top of the cover, this is the aperture Tensioner Rib, it provides downward pressure to the top of the aperture, this pressure transfers to the bottom of the base..

Do not reduce the dept of the cover tension rib, reduce the rib on the bottom of the base, this can be done with a good fine file, make complete file strokes from the rear of the base towards the front acroos the entire rib. You will remove some metal from the bottom of the base on the thin strip at the back end, that's Ok,,,, Just be light handed on the file.. If you have a Milling machine that is better.. This is a trial and fit procedure, if you go too far, a thin strip of shim stock can be place under the base.. Cut the shim stock , if necessary, the shape of he base cutout..

Make certain you have chased the thin machine cuts where the ends of the cover slip into, sometimes dross or chips of metal are left, clean these slots out and lube them along with the ends of the cover..

This in no way excuses the Company for such a blunder, but it will have your M1A up and running.. Art
 

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I had this same problem using a bm59 sight on my lrb m25 receiver. I used that same sight on another lrb te 44 receiver and no problem
Go figure
 

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Thanks for the tip Mr. Luppino. A very simple fix that was not so obvious to me. I love learning from the real gurus that have been there and done that... thousands of times.
 

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This problem can occur on any receiver correct? SAI included?
 

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just because a reciever was hard to put together doesnt mean they are faulty.

having to do extra fitment is not a statement that they are unsafe or unusable either.

asking for better qc is not a crime either but people can sue for anything.
 

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To disclose…mine was an older SAI that needed some cleaning up in a couple places.

I doubt a 'perfect' receiver is out there. Maybe there is.
 

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Discussion Starter #10
Problems on any receiver question---

This problem can occur on any receiver correct? SAI included?
Issues are possible, even some M14's were found to present problems. During the machine work it is possible for something to shift or the cutter moved..

The rear sight is one of several areas that should be held to tight specs...
 

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I doubt a 'perfect' receiver is out there. Maybe there is.
Yeah, the ones produced by Fulton Armory. By far the easiest I've ever built up. Maybe built as many as 15-20 and never a single issue short of one stubborn clip guide pin fit that only required some pin shaping. They really do build like lego sets.
 
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