I'm concerned for some reason you might get called away from the computer (to take a crap or something) and leave the gun unattended and little brother goes to play a game.
Oh no, I keep it with me wherever I go in the house whenever my parents aren't home. As for questionable characters, there really aren't that many kids his age around. When he has people over, they basically play in the basement, and my parents are home. I feel I haven't fully explained part of this situation.
The guns that are not locked up are hidden, their magazines out, and ammo stored seperately. For my brother to access and use one of the guns, he would have to get a magazine, load it with the proper ammo, insert it in the firearm correctly, pull the bolt, take the safety off, then pull the trigger. As for the HD shotgun, he would have to press the little doodad in front of the triggerguard while pumping it. My parents carry pieces are on them or within reach, in fanny packs, during the day. He wouldn't get to them. For my brother to find and use my revolver, he would need to find and unholster it, then find a way to pull a 12 or so pound trigger. We are currently looking for safes anyway.
I'm not trying to justify keeping the guns out, but we have done as much as we can without safes or locks.
I think my actions were justifiable Quartus, because if there was a real emergency, I wouldn't have the time to run upstairs. I'm not real fast. Same reason why people carry, you never know when you might need it, and it's usually the time you don't have it that you do need it.