In researching forgings for firearms I stumbled across US Patent 6711819. This patent covers the manufacturing of the scadium alloy revolver frames and cylinders that S&W uses for their lightweight magnums - Models 329, 357, and the smaller 336s etc.
The patent describes the manufacturing including forging and heat treating of the parts to make them suitable for use in magnum firearms. One thing that caught my eye was the statement that castings were not strong enough for aluminum alloy firearms in heavy calibers.
I had always wondered why Ruger never make an alloy revolver like S&W and Colt - now it appears I know the answer. Cast alloy frames just are not strong enought to take the pounding of the heavy loads.
The link is: http://www.patentstorm.us/patents/67...scription.html