Hard as steel,huh???I bought an american black walnut plank from my past employer,more like brother after 10 years,and this stuff had been air drying in a steel barn in Grayson,Ga for 20 years,was cut in south georgia somewhere.
I squared up and planed a 3'x6" board of it several years ago while still in grayson ,and was amazed at how heavy it was,finished dimension.When my bud Bob and I got the plank cut up into stocks,he was remarking how heavy.He got one of his wva walnut blanks,same pattern,and mine was nearly twice as heavy.Well,let me tell ya,twarnt no picnic working it either.Built a small buggy gun from the worst piece,really interesting flame,but lord,what a job.Currently working a 42" fullstock,not as much figure,but still like working steel.Mill bastard file works as good as 49 nicholson,well,sorta.lol.
Good luck with it.Loved my time in the Southland.
Dave up here on the mountain.