J.P. Sauer & Sohn produced and distributed the P220 after SIG created it in 1975. Both SIG Sauer companies Sauer GMBH in Eckernförde, Germany, and SIG Sauer, Inc. in New Hampshire, United States—are actively producing it. Along with many other modifications, a new locking mechanism called the SIG Sauer system was also developed. By removing grooves from the slide and barrel, the SIG Sauer design went one step further. Instead, a chamber expansion latches directly on the slide's ejection port. Inspired by the J.P. Sauer & Sohn 38H handgun, the P220's double action/single action trigger is a SIG Sauer invention. A hammer decocking lever and a robust firing pin block safety are other design improvements. The P220 variations, like many other modern pistols, lock the barrel and slide together using an expanded breech section on the barrel locking into the ejection port in place of the locking lugs and recesses machined into the barrel and slide. In addition, the P220 has an automated firing pin block safety that is activated by the trigger mechanism.