Boy those Barn Swallows are vicious birds! I know they're great for pest control but good Lord are they scary things. There were several of them at the reining barn where I used to work and I felt like I had to carry a broom with me everywhere I went for fear of being dive-bombed, lol.
That, and they seem to be really good at keeping other pest birds out of your barn. I don't know if Sparrows or Starlings are a problem where you are, but they are here, and they would NOT allow other birds inside the barn. So that to me was worth all the fear, hehe.