[My reason for researching origin is to purchase and install the correct Williams gun sight. I purchased a Series 5D-94-36 for my rifle but it doesn't seem to fit.]
Maybe we can help you here - what is exactly the fit problem ?
Let me expand a bit.
If your rifle is a top eject, the sight is correct, and should fit the two small holes in the left receiver wall at the upper rear, after removing any filler plug screw in the holes.
If your rifle is an Angle Eject, with the right top of the receiver (wall) slightly lower than the left - then you have purchased the incorrect sight, and need to exchange it for an 5D-94SE, which fits a Model 94AE angle-eject (side-eject).
The correct sight for an AE would mount atop the rear of the receiver top walls, straddling the bolt - and require a higher front sight than issue, in order to zero the rifle (it will shoot too high with the peep all the way down, with the issue height front sight).
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