Thanks Swirt.... I had a heck of a time trying to actually find and buy 3/8-16 brass hex bolts. However, I used steel because this hammer is for tapping the top end of the blade. In thinking about it, I felt steel would be better. Brass ends would get dinged up striking the blade's end. 
I also made threaded wooden ends that can be swapped out for one or both of the brass plated steel ones.