While Glock assigns individual model numbers to guns with different calibers, Sig Sauer takes a different approach. Their model designation, the P229 in this example, refers to a basic size and style of pistol, and is available in various calibers. For example, you can order a P229 chambered in 9mm, .40 S&W, and of course, .357 Sig. As I write this, there are at least eleven variants of the P229 family, each available in different calibers. Some have threaded barrels, different finishes, and even different action types.