I might as well get my two cents in. Have not seen every Hawken, so cannot say all, but many have cast off. First you must accept that every Hawken built over 30 years or so was not identical. There were variations in hardware as well as stock shape. Expecting every Hawken to look like an early 1850's half stock plains rifle. is a common error.
As far as the thinness negating the need for cast, I see it just the opposite. The cast off helps the skinny crescent butt fit into the shoulder socket
More cast in the toe than the heel helps too. I like 1/4" at heel and 3/8" at the toe. Try it you'll like it.
Art Ressel(The Hawken Shop) Had most of the molds for his castings. made directly from original Hawken rifles. Not all parts came from the same rifle . His breech tang actually had more cast than the stock pattern he developed and had to be straightened some to fit his stock. His stock pattern was not taken from any specific rifle and was changed more than once to correct errors in the initial pattern. The stock pattern was modified again when Art sold the business.
Mr Briers photo give you a goood sample of how it should look
