I think that if you go to sigforum.com, you will find that the general consensus is that any modern SIG P series (except the P210) is OK with factory +P+ ammo. There are some very knowledgeable folks on sigforum such as the folks from Gray guns.Dave2 wrote:Careful, a lot of (most?) guns aren't supposed to be fed +P+ ammo. I know it's a nono in my Sig.
I think the reason many mfg's don't list +P+ as acceptable in their guns because unlike +P, there's no ANSI/SAAMI standard for 9mm +P+ ammunition. SAAMI 9mm standard only goes up to +P. There is however an industry consensus that +P+ should be about 15% higher in pressure than +P.
As with anything, the use of +P or +P+ will accelerate wear and tear on any gun. AFAIK, modern SIG's have no problem accepting +P+ ammo.