I grew up in a small town in central California. High School in the early 80's - lots of kids from ag/ranching backgrounds would park their trucks in the school parking lot with a rifle or shotgun hanging in a rack in the back window. I don't recall anyone being particularly bothered by that practice or any problems relating to it.

Same town, different era: My 12 year old nephew received a poor grade and "this is terrible!" written on his essay by his teacher because "What I did last weekend" recapped target shooting with his dad and grandpa at the range.