Surefire brushed knurled brass king is awesome. the lock ring operates on LARGE threads. Barely have to turn the sucker. It gets a little sticky locked in either position. Just enough not to spin of locked by accident. I can tighten them tight either way and undo it easily. I also use nyogel 760g, so that make it feel like a ball bearing. Kind of remind me of the stickiness you get from hardened titanium on hardened steel. Its a good sticky.
To get stuck unstuck, get a piece of leather and vice it down, grab the exposed with a wrapped around rubber band or grip rubber. If you are having sticking issues try some grease, but believe it or not, grease could make it worse. Grease allows threads to torque down even more due to less friction...
Good luck!!