1. The Henry Golden Boy has a receiver cover and barrel band made of Zamak 5 plus a brass buttplate. Here's info on Zamak which is an alloy of zinc, aluminum, copper and magnesium:
http://en.wikipedia.org/wiki/Zamak
Andy Wickstrom of Henry subcontractor Henry Wisconsin which produces the receiver covers and bands had this to say about their Zamak alloy:
"First, the metallurgical standard for this metal is Zamak 5. Inside of the Zamak 5 spec we maintain even tighter control of certain elements to further improve physical properties. Second, the metal is cast using the ultimate in high pressure die casting equipment. The power and speed of this process is impressive. The process used to control the quality of the product consists of countless variables that are finely tuned to produce the very best physical and cosmetic properties."
On the Golden Boys the Zamak receiver covers are coated with "Brasslite" which is a brass-tinted clear coat paint.
2. On the other hand, the Henry Big Boy has a hardened brass receiver, barrel band and buttplate.