No one knows for sure.
However well mainainted meaning that the frame rails are well lubed with many of use using grease, and the recoil springs are changed every 5000 rounds an alloy P series SIG such as the P226 will last a very very long time. I would think 60,000 rounds could be expected and there have been numerous reports from reliable sources of alloy frame P series SIG pistols frames lasting past 100,000 rounds.
My SIG P series are all alloy frame because I appreciate the lighter weight though I probably will buy a P226 X-Five Allround at some point for a HD/range pistol.
If I ever wear a frame out on one of my alloy frame SIGs I will have spend probably close to $15,000 on ammo by then to put through that pistol.
Good luck with your choice!
Last edited by sigarms228; October 2, 2012 at 06:44 PM.