It’s foggy now, but I’m thinking...a notch that lined up with the part that sticks up at the end of the barrel? But that could be adjusted side to side?
8,974 posted on 11/30/2007 7:16:28 PM PST by RosieCotton
("Anything worth doing is worth doing badly." -- G.K. Chesterton [NaNo Count 50400/50000])
_Fig_4-17.png/593px-M16_rifle_correct_sight_alignment_FM_3-22.9_(23-9)_Fig_4-17.png)