I found that when the string hits clothing it makes a loud slapping sound that you should notice. If this isn't the case, I'd check out the ideas already posted. A heavy head on carbon shafts can sometimes fly funny. I went back to alum. shafts and solved that problem. Do you use a range finder? I can tell the difference between 1/4" and 5/16" just by looking, when it comes to yards with trees and such in the way all bets are off. I read a post about a sale at JCPenneys and checked it out. Wonderful bargin and hunting tool.