Staff Writer (Updated: 5/9/2016):
At its core, the P220 was a revision of the original P210 system appearing in the late 1930s. The SIG concern purchased several French-based patents and began the design and development of their own automatic handgun with the resulting product becoming the P210. The P210 featured a locked-breech pattern not unlike the original Browning design and made for a solid and reliable weapon. The P210 had the ability to fire both the 7.65mm cartridge and the 9mm Parabellum, the latter with some required internal alterations of course. Five versions of the P210 ultimately appeared and the type was issued to the Swiss Army as the primary sidearm. Such was the quality of the handgun that the P210 stayed out of reach for many budget conscious militaries and police forces suggesting that the gun was too expensive to obtain in any number.
The P220 was therefore designed along the same lines as the P210 before it. However, the P220 was designed as a faster and cheaper version to produce for concerned shoppers. The slide-locking feature was simplified from the original P210 and the weapon's construction was assisted by computer-controlled machinery for precise measurements. The gun was delivered to market in 1975 and entered service with the Swiss Army as a primary sidearm that same year. In service, the Swiss designated the weapon as the "Pistole 75" or "Model 75" replacing their P210s in the process.
Internally, the P220 sported a locked-breech system and a short-recoil action, each with origins based in the hugely successful John Browning system. For safety, the P220 did not disappoint with the inclusion of a de-cocking level, an automatic firing-pin safety block (patented in design), a safety intercept notch and a trigger bar disconnect to ensure that the weapon did not fire by mistake. The trigger was double-action in nature but a single-action function could be attained if need be. There was no manually-operated safety catch thanks to this integral four-point safety system. The firing action saw the slide and barrel - as they were locked together - move rearwards along the frame. The barrel was then cammed down until the bullet left the barrel. The rearward motion of the slide ejected the spent shell casing and set a recoil spring into action. The recoil spring now brought the slide forwards and the resulting action stripped a fresh round into the firing chamber. The barrel was now cammed upwards and joined the slide in the forward-moving action, readying the gun to fire once more.
The P220 maintained an overly clean appearance consistent with the SIG-Sauer brand. The slide was rectangular with smooth slab sides. The pistol grip fit well in the average hand for a good solid hold and a prawl made sure the gun stayed in the hand of the user when fired. The hammer was visible as a protrusion at the rear of the frame. The barrel was seated within the slide and measured 4.40 inches in length with a 6-groove, right-hand twist rifling pattern. The entire weapon maintained a running length of 7.79 inches. The trigger was hinged along its top section and protected by an oblong trigger guard. The ejection port was located along the top middle of the weapon frame with a notch sight seated at the rear and a post sight at the front, just above the muzzle. Support for Picatinny rails was added later. In whole, the P220 proved a solidly constructed sidearm made specifically for the rigors and abuse of everyday handling in intense lines of work.
The primary cartridge for the P220 became the 9x19mm Parabellum, these fitted into a spring-loaded 9-round detachable box magazine (also available in 7- or 10-round counts and varying calibers) inserted into the patterned pistol grip. Muzzle velocity was rated at 1,132 feet per second. Empty weight of the entire weapon system was 1lb, 13oz. There magazine release was located to the rear of the magazine well but this was later relocated to the left-hand side of the pistol grip, just rear of the trigger.
The P220 has since proved popular to its users in the security, police, military and special forces departments. It is supplied in two major versions known as the P220R and the P220ST. R-models utilize an aluminum alloy frame with a stainless steel slide (or stamped steel if produced in Germany, otherwise made in the US) while the ST-models are made with a frame and slide of stainless steel. Variants within the P220 family became the P220 "Rail" sporting the Picatinny rail system on the dustcover to accept various sights, scopes and accessories, the P220 "Carry" with its shorter 3.9-inch barrel and accessory rail, the P220 "Compact" (four variants in itself), the two P220 "Combat" .45 ACP models for military use, the P220 "Classic 22" chambered for the .22 "Long Rifle" cartridge, the P225/P6 compact form, the P245 .45 ACP for the Swiss Army and West German police (P6) and the P245 for the American market chambered only in .45 ACP.
The P220 has since been succeeded along the SIG-Sauer production lines by the P226 model. When it was first imported to the US, the SIG-Sauer P220 was marketed under the name of Browning Double Action (BDA). These were offered in .38 Super, the original 9mm and .45 ACP calibers. Since then, the P220 was sold strictly a .45 ACP weapon.