I'm thinking about buying one of the new 457-S S&W autos.  However, I'm concerned that it is assembled using an aluminum alloy frame.  Does anyone know what type of alloy the frame is made out of and what type of longevity it will have compared to the stainless steel frame?

While an all steel frame might last longer than an alloy one, I doubt that you will see much difference within your lifetime. Alloy frames have been with us since before WWII and many of them are still going strong. The odds are you'd wear out the barrel before you would wear out most any frame being made today.

Smith has used alloy frames on their autos from the beginning.  I seriously doubt you could wear one out if you tried.  You can can get steel frame Smiths, but you will pay a significant weight penalty.

For what its worth almost all 9mm & 40 autos these days are alloy framed (or polymer).  Sig, Beretta, Ruger are all alloy.  Glock, H & K, polymer.  

The frame isn't really under that much stress in an auto.  Its merely given the slide somehwere to slide and hold the trigger parts together.

Keep it clean, keep it lubed (Smith's don't like being shot dry) and the gun will out last you and your kids.

Thanks alot for the responses...  I'm going to take the plunge and get the 457-S!  

Aluminum frames are WAY more durable these days than in the past.