I do like your build, R-S!
I like the buttstock shaping, looks very right with its angles and all.
I used to get my hemp twine from Susan Wallace, at Silver shuttle. (Came in 110 yard balls)
Some I boiled in wood ashes, and some in wood ash/gunpowder mix, and they both worked well, but the gunpowder mix would catch sparks very readily, if you didn't rub it well to get the charcoal off it. (or rinse it well, and I didn't)
You can also use those "horseshoe" fungi that grow on the bases of trees.
Just dry them and slice up. the best part is the cork-like part with no spores. It will hold a Very hot coal and burn at a steady rate.
You can get a good supply of these in no time in aspen or birch woods.
Tinder-locks used these, and that's where they get their name. (In Swedish,...."Mushroom lock"!)
"Swamples lit"
P-B.