Regarding the rifle, I'm completely with you on that one. Yikes.
Val
Wow - me too. I feel lucky that none of the houses my kids visit have guns and I don't have that piece to think about.
Once I am comfortable with a family, I cut my kids loose to interact and play as they choose and to follow other families rules. Like we don't have toy guns here. But I know some of my sons friends have nerf guns they use, and I'm fine with that. We use a timer for any computer, video game time. If another family doesn't, that's fine too. I used to be a little harder on this when DS was younger, but at 9, if they are playing together and the other parent is fine with it, I'm ok with it.
My son's closest friends (2 close in age sibs) and very close neighbors (across the street), have a mom that has a very hard time cutting loose on some things. She really wants to intervene when the kids are arguing or disagreeing. And I feel pretty strongly that as long as they are not being wildly disrespectful or mean, I want them to hash these things out. These are also quite GT kids (especially one of them), and they are all very opinionated. I think it's a good skill for them to learn to compromise and work together. I'm fine if a play date gets cut short because they get too frustrated. They are all such great friends, that it would be fine the next day. Having my kids at home constantly has increased my tolerance for this. I find myself intervening less having them around more. I regularly have conversations about respect and team work. I just like using natural consequences for social interactions.