I understand the need to be cautious. At the same time, I also think that my kids need to learn independence and skills related to making good judgements.
If I don't know people well, I suggest that we meet at a park for a playdate. I figure they don't know me any better than I know them yet, so everyone seems to be happy. But I rarely get involved when my eight- and ten-year olds are playing with their friends. I keep a closer eye on my five-year-old, but I still don't hover.
To me, it seems a bit of a strong reaction to bar your kids from playing in someone else's house because they were wild on one occasion. Many boys can get very physical; it's who they are.
Regarding the rifle, I'm completely with you on that one. Yikes.
Val