scared the dog catcher tonight

We have 4 Shi Tzus so when a strange pit bull came into the yard tonight my wife called the town dog catcher, usually he won't bother coming down but my wife told him if it came into out fenced yard we would shoot it, I have about an acre of yard fenced in so i don't have to worry about my dogs getting hit or my kids, so i figure if a dog comes over my fence it's legal game, so he came right down, I have my half-track sitting outside the garage because I'm working on it right now, it has a dummy .50 cal sitting in the pulpit mount, from a distance it looks real and he noticed it right off, is that legal, why do it have a machine gun? The typical questions I get any time some one rolls into the yard and I have it out,I've even had cops take a real close look at it, it's probably the funniest part!