I'm pretty sure on the Sig P226, but might possibly end up with an H&K USP .40 or .45. Anyway, the P226 comes with a .40 S&W barrel but can be interchanged with a .357Sig barrel. What are the advantages and disadvantages of each ammo type, is one more accurate than the other? Does one do more damage than the other? Which ammo is cheaper? I really like Sig guns and have shot a few and they fit me well, so I think thats what I'm going to go with, I just need to decide which barrel I want to start with. Thanks for any info!