Sounds like your nocking point is too high , and you are shooting too weak of a shaft . 4" offset feathers will allso probably help you . 5 shots link I' m sure will get you pointed in the right direction , but just in case heres a link to eastons allso , If I were you I would make sure I was shooting the properly spined arrows , sounds like your on the week side if when you go to a heaveyer tip you groups get worse . Then skip down the link I gave you straight to broadhead tuneing . Good luck and let us know what worked for you .

http://www.eastonarchery.com/news/tu...ning_guide.pdf