Gv, welcome to the world of "what do I do now".
I build my onw soft srings( thats what we call low strand strings)I have found out through trial and error one will need to get several diferant size survings to do what you want.
What I ended up doing was making a string about 15" long and the serving it. Test the nock strip it down and do it again untill I found what worked.
Just a list of some of the servings that I have,.018,.020,.025,.030,I also have 2 rolls of silk serving that measure.013,and.017. The silk is used as a sublayer not as a final seving just does not hold up in my opinon.
Do a search on this subject and you will find several enteries that have differant ways of doing what you are trying to do.
Hope this helps...
Later.....Buzz