I am shooting CX 300s with the black shafts and I am shooting them through the small biscuit, i used to shoot them through the medium sized one but my accuracy was terrible with it so i switched to the smaller one. I still have plenty of room around the arrow so its only rubbing on the bottom of the arrow, I guess its one of those things that i did not pay attention to in the summer. It is definitely the biscuit as i drew back with no arrow in and it was dead quiet.