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hmm, could be buffer size.
the stock locks in place for shouldering, but after shooting, it collapses right back in
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Not sure it is the buffer size, as SOPMODs are on the military size, 1.14" and if it were a commercial tube, 1.17, the SOPMOD would not slide on. The screw on the bottom adjust the depth of the engagement of the pin that locks into the extension tube holes. Once the adjustment is set, proper depth, there is a roll pin that keeps the screw from backing out or in, keeps the depth correct.
Can you measure the extension tube dimensions?
Is the extension tube new? Excessive wear in or around the holes?
This is baffling, please post pictures, so we can see what is going on. This screw is the only screw on the entire butt stock.
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