HOW TO ? /the best way to "lock" a Mag-lite head

[JamisonM]

I use thread tape, The PTFE stuff, for sealing pipe fittings, You can put on as much as you like, and have the tention set, and its still movable, just not that much.

I use it because I always have a roll on me at work...not necisarily the best though when looking at the solutions here, after taking the head of a few times the tape shreds up a bit and i pull it of and rool on a bit more.

I may look into a bigger oring and smearing a bit of the GF's hairspary on with a finger.

I do the same thing, but with a short piece of electric tape. Put a piece around an inch long on the lower 3/4 of the threads and screw the head on. You'll know when you hit the tape when the head becomes hard to turn. Keep turning to the desired focus and leave. You can still turn the head, but it may give you a run for your money.