I just did a bow with back strap sinew,,
I had never used it before,, it was a little more coarse for me too,,not quite as smooth
but it went on nice,,and the bow turned out nice,, and it was faster to apply since it was so long,,
I am sure there are ways to make it as smooth as the leg sinew,, probably pats method would make it really nice,, did you try wrapping it,,??