Joezx10r, I had the same question when I started my 17hmr ar15 bolt (not done yet). I sent wolf a question and they answered the question. I can't remember what it was, only that a standard buffer spring would work for me. I'd sent wolf and email.
I entered in the wire size, diameter and number of coils in one of those online spring rate calcalators when I posted this question and it said only a few pounds. Just didnt sound right.