Went to the range today. Checked the essentials before heading out the door - ammo, mags, cleaning kit, and optics have power (two Aimpoint ML2).
I happened to shake both & one rattled. A faint metallic "tick-a-tick-a" sound. Uh oh.
Remove batteries - still hear it. All caps snugged down - still there. Check the LaRue mounts - solid. Pop open lens covers - crap, it's louder!
The culprit was the lock ring in front of the objective lens. I was able to re-tighten it with a derlin pry tool from an iPad screen repair kit. It could be spun freely in either direction. Doesn't appear to affect zero or water resistance. Has anyone else had this happen or lost one in the field?