A good place to start is viewing the video " A LOOK INSIDE HOLLAND & HOLLAND". In the section on stockmaking several different types of chisels are shown that are common to stockers. I am confident this video is available in America.
As the photos in the reply above illustrate, stocking tools should be made in short to medium lengths as compared to say cabinet makers chisels. Almost all stockers make their own chisels as they find their individual requirements dictate this. Silver Steel (called drill rod in America)can be used to make chisels and turn screws. Better to use W-1 vs. O-1 if you are not experienced with heat treating, however.
And whilst I mention cabinet makers: the English cabinet makers turn screws make the best heavy duty gunmaker turn screws after they are re-ground and heat treated on the tips. I have two sets of the Sheffield made cabinet makers turn screws (Crown brand, I seem to recall)--one set for use and one for backup. Of, course I have a great deal of the traditional gunmakers turn screw that I use as well.
