[4] In the United States this handgun was originally sold in a modified form as the Browning BDA from 1977 to 1980.

The recoil spring moves the slide forward again, inserting a new cartridge from the magazine into the chamber and cocking the trigger.

The slide of the P220 series is a heavy-gauge sheet metal stamping with a welded-on nose section incorporating an internal barrel bushing.

The breech block portion is a machined insert attached to the slide by means of a roll pin visible from either side.

The SIG P220 series incorporates a hammer-drop lever to the rear of the trigger on the left side, which first appeared on the Sauer 38H before World War II.

Further design refinements include a hammer decocking lever and positive firing pin block safety.

[6][7] The P220 also features an automatic firing pin block safety which is activated by the trigger mechanism, similar to the one used in the Czech CZ-038 from the period after the Second World War.

The first shot will be fired in double-action mode, unless the user chooses to manually cock the hammer.

As with other double-action pistols such as the Walther P38 and Beretta 92F, some training is required to minimize the difference caused by the different trigger pressure between the first double-action shot and subsequent single-action shots when the hammer is cocked by the rearward movement of the slide.

On 17 July 2002, he was "accidentally shot and killed when his Sig P220, .45 caliber service weapon, fell to the ground and discharged, striking him in the head.

He had gone to the police station to pick up a patrol car...as he walked across the parking lot, his weapon, still in its holster, fell to the ground and discharged when the hammer struck the pavement.

Newer SIG P220s utilize a push button magazine release to the left side of the grip, behind the trigger and do not have lanyard loops.

The R and ST models also have a Picatinny rail, beneath the slide and barrel, allowing for fitting of accessories such as lights or laser sights.

Originally, all SIG P220s were DA/SA and featured a decocking lever (and no external safety) just forward of the slide catch.

SIG has also introduced the SAS (SIG Anti-Snag) model—which is dehorned, has no accessory rail, and is designed for concealed carry—and the Elite model, which includes the new short-reset trigger, a beavertail grip, front strap grip checkering, and front slide cocking serrations.

[10][better source needed] The P220 was initially imported to the United States as the Browning Double Action (BDA) [a] and then as the Sigarms P220.

These particular P220s (or Browning BDAs) will have the stamping scroll which reads 'Browning Arms Company Morgan, Utah and Montreal PQ' on the left hand side of the slide and 'SIG-Sauer System Made in W. Germany' on the right-hand side with the serial number scrolled beneath.

The Combat model comes with night sights, a Nitron-finished slide and barrel, phosphated internals, and a Picatinny rail.

The Classic 22 also has a different barrel, guide rod, and recoil spring than the larger caliber models.

[22] Another difference is that the Classic 22 is manufactured by SIG Sauer while the Mosquito is made under license by German Sport Guns GmbH.

The frame is modified from the base model with a reduced and contoured beaver tail, an undercut trigger guard, and front slide serrations.

[24] A limited edition P220 Legion Carry SAO was released in 2020, but was only produced in small numbers before being discontinued.

Walter Ludwig was involved in the design of the Walther, SIG-Sauer and Mauser entrants in the German Police selection.

Initially, the P220 was submitted; the P225/P6 was a revision created to conform with the mid-1970s West German police requirements for its standard service pistol.

There was a new contour to the frame, a short reset trigger, a milled slide (the earlier one was stamped), and two barrel lengths (one standard and the other threaded for a suppressor).

[31] The SIG P245 variant is chambered only in .45 ACP (hence the name) and was developed primarily for the US market as a civilian's concealed sidearm, or as a police backup weapon.

[32] The SIG P245 has a reversible magazine release giving the user the choice of operating it with their left or right thumb.