I made a 50# bow yesterday, with a hemp string instead of B-50, and used the 2-3/4" measurement. The string was way too short.
So I made a new string and measured it. The hemp string is 1-1/4" shorter than the nock-to-nock measurement. I use hemp for lower poundage bows and the kids' bows but decided to try it for a hunting style bow.
Hardly any stretch in the hemp. I like it.