I've had my DPMS rifle for three years approx. and I've only recently started shooting it (long story) but I now know that I'm missing (and this is the only way I can describe it) screw 8 as illustrated in the USMC TM 05538C-23&P/2 manual page 3-41.
It's the hex screw that apparently locks the rear sight's range marked elevation index to the elevation knob. Mine has always rotated freely but I didn't know that it was able to lock down.
WHERE can I obtain such a screw? I obviously DON'T want to purchase a new rear sight.
I'm NOT asking DPMS to give me one, and would gladly pay for it, but is this possible? OR where could I get one third-party?
It's recently become a pain ITA.
Edited to add:
I bought this rifle new (and it was, by inspection) so I don't know why this hex-screw is missing...