Hop Astringency

This is a topic that I have been doing a little research on lately and trying to gain an understanding of.  I've been finding that my hoppy summer ales have a slight astringency that presents as a dryness in the mouth.  It's only subtle and not unpleasant but I would like to understand how to control it.

I'm confident that the astringency is not related to any other aspect of my process other than the high hopping rates relative to the body & sweetness of the beers. 

Is there a trick to reducing the astringency in highly hopped, light coloured beers?

Can the stringency be reduced without simply masking it with more body and/or sweetness?

At this stage I am planning on juggling my hop additions until I find a way around it but I would hate to think that I'm barking up the wrong tree.

Here's an example recipe:

http://www.forum.realbeer.co.nz/group/nzcaseswap/forum/topics/cs5-m...

Cheers!