What are the main differences of these materials?
B-55 is slightly smaller diameter than B-50 but other than that, not much.
Most users will say, and I agree, B55 stretches a little less. B55 is all I use to make strings for myself.
Welcome to the forums Justen.
Bud
I find B55 slightly larger diameter per strand more then B50.I use a smaller diameter serving on a 14 strand B55 over a 14 strand B50 for the same nock fit.