Well, first of all, I've just found out that Symbiant's 'Locked Doors' mod DOESN'T ACTUALLY WORK. I built a small metal shack, stuck a locked door on it, and put all my guns inside. I come back a while later and... find Nick Valentine sitting inside it, staring at me when I open the door. So yeah, still need a viable solution. As for why my stuff gets stolen... it's PROBABLY because of a certain stylistic choice of mine, that seems to be quite unusual: I like to stick all the ammo in the same crate as the gun. I find it... immersion-breaking that I can carry around 6000 rounds of 5mm ammo all the time, so I store it in a crate along with my minigun, so that I can easily collect both gun and ammo when I feel like taking it out for a spin. But yeah, you do that, and everyone who can get to it WILL steal your gear, AND use it. (At least keeping all the fusion-cores with me prevents my powered armor from being stolen... but once again, I can't store the fusion-cores anywhere, since then THEY will just be stolen, and used to power the armor, which they will then use.) So... maybe I can get around this whole problem just by ignoring the ridiculous amounts of ammo I'm carrying, or by storing it in a separate crate, but then I'll have to go through a list of 20 different kinds of ammo when I need to collect something, and try to remember what I've got all my guns chambered for at the moment... so yeah. I'd still much prefer having some way to get everyone to just keep their filthy mitts off my gear. Oh, and maybe I can also get around it by equipping all my settlers and unused companions with decent gear, but c'mon! My companions have INFINITE-AMMO weapons they can use per default, they should be happy with that! And my settlers are just supposed to run the stores and look after the crops - I've got a ton of turrets set up around the settlement to deal with attackers, so they really aren't SUPPOSED to be getting into scraps!