Personally I don't know where all the "circular tiller gives you hand shock comes from"
Maybe what I call arc of a circle tiller isn't what others call circular.
The only hand shock I've ever had from a longbow was from a heavy hazel warbow that was very wide in the grip and an uncomfortable shape which sat poorly on the knuckles. I have made quite a few
Maybe what follows is one explanation for hand shock?
I have seen suggested layouts like this:-
a) Straight grip section (say 6") and then taper the thickness from there.
That is so wrong on many levels, as it is actually making the grip weak!
b) Thickest part is actually at the centre, tapering from there.
That makes the grip stiffer than in "a".
c) Lower weight bows often have the grip thicker for comfort, often achieved by gluing a short riser section, this obviously gives a stiffer grip, gives a more elliptical look (regardless of the actual curve on the limbs) and help stop any hand shock.
Del