I've made three bows from walnut so far and have to come to love it for a bow wood. Quick, quiet, light in the hand and gorgeous wood. For 50# I would aim for about 1 5/8-1 3/4" wide limbs and heat treat it. It does very well with a good heat treat though because it's already dark, it's hard to see how it's taking. So go by the feel of the wood and the smell. You sense a shift in smell when the wood is hot enough, in addition the the back of the bow being warm when your heating the belly side. Of the three, the best look I got was getting the sapwood down to a thickness so that the heart wood started in the fades and petered out midlimb. That way you can get more of the greens, blues and purples to show. The last one I did was almost entirely heartwood where the very last transition ring was used as ye back. You can find it being built in this years bow trade thread. It was made 1 5/8" wide to midlimb before tapering to 3/8" tips and was heat treated, coming out at 55# at a 27" draw. It shoots very quick and extremely quiet, it sounds like an average wood bow with string silencers, when this bow doesn't have any.
And go SLOW with good light when chasing rings on walnut, I would use a scraper to chase the last few rings. It's doable but will give very good practice for when you work another osage stave. It seems like walnit can handle some violations, just feather them out well with a smooth transition if it does happen.
Kyle
