I think the key is making sure your inserts are square. I like the Easton ST, with the Hidden Insert Technology. They align the insert with the wall of the shaft...so much less likely to be, well....UN-square!

When you have the inserts in and the broadhead on (make sure its tight!), spin the arrow (on some sort of frame). You can often see a "wobble" if the insert isn't in square.

Having said all that, I will tell you that 9 times out of ten (for me), its my poor form that screws up my arrow flight. Have someone watch you shoot, or better yet, set up the video camera.

That's all I know...and I'll be the first to admit that its not much!

I do know this, though....both my Slick Tricks and my Magnus Stinger BuzzCuts are DEAD ON with my field points!

Good luck!