I've been reading several posts on arrow spine and it's left me confused. What are the problems with an under spined arrow?
What are the problems with an over spined arrow (I've only heard of being underspined, I assume because everyone wants a lighter arrow)?
And the charts are just a starting point right?

I was shooting GTpro hunters 7595's Hardwoods (spine is 300) and they shoot fine, quiet, and accurate (with vanes or feathers).

I just bought some ST AXIS 400's (spine is 400) and they shoot well but the arrows I put feathers on make noise. My thought is they are probably a little underspined and the noise is caused by the feathers working (over working).

Your thoughts?

Thanks