I agree with the others, sounds like a tuning issue. As for the Thunderheads, i've been shooting them for 16yrs and i've never had a problem what so ever getting them to tune with any set-up i've used. I've never tried another broadhead because i've simply had no reason to switch from the Thunderheads. They impact with my field points and fly like darts. I think any broadhead will shoot with accuracy with a properly tuned bow. Like i said, it sounds like a minor tuning issueprobably something simple that maybe you've overlooked. Find yourself a bow shop with some knowledgeable people and see if they can help you out. I know it's gets frustrating at times because it has for me, but don't give up!