I recall reading years ago that S&W was alloying the aluminum they used in frames with 7% scandium, and that scandium came from Russia. Scandium alloy frames still stretch, shimmy, wiggle, and shake, but it makes the frame return to its original dimensions much better after firing a scandium alloy gun versus one that's not. An aluminum frame will get "sloppier" dimension wise compared to a steel frame with the same number of rounds. A scandium alloy will cut down on the slop and the gun will stay tighter longer.

Anodizing hardens the surface of aluminum and makes it more corrosion resistant. It also makes the surface non-conductive.

Bill