I bought a Surefire Scout, and I thought I read that you're supposed to lock out the light when not in use. I don't know if this is to prevent damage, prevent battery draining, or what. Do you lock out the head or just leave screwed down. Thanks in advance.

Never heard of this. I unscrew the battery cap a little so it doesn't get inadvertently activated. I guess the same thing can be done with the head.

I'm betting an 11B will be along soon to explain why.

Anyone else?

Lockout tailcaps are a feature listed for most all SureFire flashlights. It's not as complex as you'd think; back off the tailcap a certain amount and it will no longer complete the circuit. Helpful for storage (if there is a chance of something bumping into your switch) but not necessary to prevent a parasitic drain. It's more difficult to do this with the pressure-switch remote tailcaps; in those cases, I would probably just un-plug the switch if my rifle was going to be bouncing around in a gun case.

I have mine with Unity Hotbuttons. The plugs are tight fitting. I just unscrew the end cap a little and it's good.

OP, are you referring to the Vampire heads (that switch from white light to IR)? Because they have (had) an OFF position in the middle between IR and WL. I read somewhere that Surefire did away with this feature recently but I dont have any new ones.

It's a mostly useless feature inho except for tactical environments where accidental light can be dangerous.

Other than that, the lockout tailcap is just simply unscrewing it to the point where pushing the button no longer activates the light. I use this on light that go into a suitcase or something where accidentally turning on is possible.