CompM4 Battery Screwed Out

I went to change out batteries in my CompM4 a few days ago and and the battery cap was stuck. Grab some pliers to break it free and ended up unscrewing the entire battery tube assembly from the body. Contacted Aimpoint and evidently it is an old military serial number so they won’t work on it. I was finally able to get the battery cap off today with judicious use of vice grips. Everything appears to be working still so I think a new battery cap should get me up and running but I had a couple questions.

Does anyone know the size of the O-Ring that is on the battery tube? I stretched mine out trying to get the cap off.

Would you locktite the battery tube back into the body?

The CompM4s owners manual I have doesn’t call out the O-ring size, but I think anything that will fit the groove will be adequate. Be sure to lightly grease the o-ring and threads with a dab of silicone grease once you get a new battery cap. The threads do tend to gall over time.

I have a habit of cleaning and lightly greasing threads on flashlights and sights like these, as well as turret caps, because sometimes you find machining chips and other assorted FOD on even the best of parts.

I would think red Loctite or Rocksett would be the way to go to permanently re-mount the battery tube to the body. Go sparingly.