The 10mm Auto SIG P220

The 10mm Auto SIG P220


ABOVE: The P220 chambered in 10mm was tested with many different types of ammunition including Hornady Critical Duty, Hornady Custom, Buffalo Bore as well as SIG Sauer V-Crown™. Pistol functioned perfectly.

When one asks who makes one of the best military/law enforcement grade pistols in the world, one of the first names put out is SIG Sauer. Their reputation is spotless with emphasis put on their utter reliability and durability. In the beginning, SIG Sauer pistols were designed in Switzerland by what was at that time SIG Arms AG and the pistol was manufactured in West Germany by EckernfÖrde which was a subsidiary of J.P. Sauer und Sohn GmbH. The original SIG P220 was adopted by the Swiss Army in 1975 to replace the single action SIG P210. The P220 designation in the Swiss Army was the Pistole 75 or P75. This pistol, like the SIG P21 before it, was chambered in 9x19mm.

The pistol operating mechanism is the locked breech short-recoil designed by John Browning. The slide and barrel are locked together. When the pistol is fired, the slide moves rearward after pressures have dropped and the projectile has left the barrel, disengaging the barrel hood from the slide. This permits the slide to move rearward. The extractor has hold of the rim of the cartridge case pulling it out of the chamber. As the slide continues rearward the base of the cartridge case is struck by the fixed ejector throwing the cartridge case out of the ejection port on the slide. Once the slide meets its full rearward movement, the recoil spring returns the slide forward. The bottom of the slide pushes the next cartridge out of the magazine. Upon further movement the rim of the cartridge slides up the breech face under the extractor. The round is now fed and chambered into the barrel. With the last part of movement the barrel is cammed upward and the hood reengages the front of the slide, locking the barrel and slide together.

The P220 chambered in 10mm (top) is visibly larger/longer than the 9x19mm P226/Mk25 (bottom). This is especially noticeable in the grip of the frame. P226 is noticeably wider. The complete stainless steel frame and slide made the pistol much heavier.

The slide of the original pistol is manufactured from a heavy gauge sheet metal stamping. The front of the slide is welded. The barrel bushing is part of the slide itself rather than another separate component. The actual breach is a separate component that is pinned into the slide and held in place by two spring pins. One is driven into the center of the other. The breech face itself was not hardened. Another unique feature of the SIG pistol was the passive firing pin block that remained engaged until the trigger was pulled all the way to the rear.

The frame was manufactured from an aluminum forging. After machining and deburring, the frame is hard coat anodized black. The magazine release is located on the butt of the pistol. The single column magazine held 9 rounds of 9x19mm ammunition. The pistol’s trigger is a double/single action trigger with no manual safety. The double action trigger specifications are from 12 to 14 pounds. After the first long double action pull the trigger is single action, which was half of that, approximately 6 pounds. The pistol is equipped with a decocking lever on the left side of the gun. When the pistol is in the single action mode with the hammer back, the lever is pulled down and the hammer is slowly decocked. The hammer cannot strike the firing pin and rests off of it.

The barrel is 4.4 inches in length. The recoil spring is manufactured from braided wire to increase service life. Many of the SIG pistols have an extremely small compartment for the recoil spring. This means that you cannot use a longer spring which would be required for more durability. By using a braided spring, you can extend the service life greatly over the same length spring with a single coil.

The P220 in 10mm (left) is noticeably longer than the P226/Mk25 in 9x19mm (right).

Basic disassembly of the pistol is simple and requires no tools. After removing the magazine and ensuring the pistol is empty the slide is held to the rear by retracting the slide and pushing up on the slide lock located on the left side of the frame behind the decocking lever. Now with the slide locked to the rear, the disassembly lever which is also located on the left side of the frame is rotated downwards. Now the slide release is depressed or the slide is pulled fully to the rear and the slide is slid off the front of the frame. Next the slide is turned over and the front portion of the spring guide is pushed inward towards the muzzle and the spring guide/recoil spring assembly is lifted out of the slide assembly. The barrel can now be lifted up and out of the slide.

The P220 would enter the United States by way of Browning Arms as the Browning BDA or Browning Double Action between 1977-1980. The pistol was offered in 9x19mm, 38 Super (very rare) and the All American 45 Auto. Browning discontinued the BDA after only a few years due to poor sales.

With the introduction of the SIG P220 in 1984, there was very little interest in the lower 9 round magazine capacity compared to the P226 with 15 rounds. The P220 would really be known as the 45 Auto caliber SIG. At the time of its introduction into the market, the P220 was one of a very select few companies offering a modern double action pistol chambered in 45 Auto.

The P220 in 10mm has the tradition SIG-type controls. Notice the disassembly lever, de-cocker and magazine release button.

The 10x25mm or 10mm Automatic round is one of the highest power auto loading pistol calibers in the industry. Developed by Jeff Cooper along with the Bren pistol in 1983, the round was developed to exceed the ballistic performance of the 45 Auto and to have better knock down power than the 9x19mm. Once the initial ammunition went into production by Norma, the ballistics were improved to bring the 10mm to the power level of the 41 Magnum revolver cartridge. The 10mm has a flat trajectory with significant power as well as recoil. The pistol it was designed with, the Bren Ten, was based off of the proven Czechoslovakian CZ75 double action pistol. The Bren Ten suffered from many mechanical problems. Some were design flaws and others were the difficulty in firing such a high power cartridge. Many pistols chambered in 10mm have suffered from durability problems. In 1986, production of the Bren Ten ceased. At the time this was the only pistol firing this cartridge in the industry. The cartridge was saved in 1987 when Colt introduced their Delta M1911 pistol chambered in the 10mm Auto. This saved the 10mm from becoming just another wildcat cartridge. Other companies went on to make pistols chambered in the 10mm Auto such as Smith & Wesson, Glock and in 2015 SIG introduced their P220 chambered in this caliber.

The 10mm cartridge has a projectile with a diameter of .40 inches or 10.17mm. Projectile weights can vary from 155 to 220grains in weight. The cartridge case has an overall length of .992 inches or 25.2mm and uses a large pistol primer. The cartridge overall length is 1.250 inches per SAAMI specifications. Maximum pressure per SAAMI Specifications is 37,500 pounds of pressure per square inch. Factory ammunition is manufactured by almost all the major manufacturers including Federal Premium, Remington, Winchester, Double Tap, CCI, SIG Ammunition, Buffalo Bore and Underwood to name a few. Most common projectile weights are 180 and 200 grains. Projectiles include full metal jacket, hard cast lead, Gold Dot, solid copper, bonded hollow point, Hydra-Shok, Hornady XTP/Critical Duty, jacketed hollow point, Black Talon. Double Tap ammunition is particularly well known for their wide offering of 10mm options. The typical 180 grain projectile has a muzzle velocity of approximately 1,030 to 1,275 feet per second. Many of the target loads (Remington UMC 1,150 FPS, Hornady 1,077 FPS) are loaded to a lower velocity. When you look at the same projectile weight of 180gr loaded by other manufacturers (Buffalo Bore 1,350 FPS, Double Tap 1,305 FPS, Grizzly Ammo 1,300 FPS and Underwood 1,300 FPS) they are to much higher velocities. The other popular weight is 200 grains. These velocities average between 1,050 and 1,200 feet per second. Some of the lighter 155gr projectiles have muzzle velocities from 1,265 to 1,500
feet per second.

The P220 chambered in 10mm disassembles into the same basic components in the same way as the entire SIG family of non-polymer pistols.

The first real acceptance for the 10mm Auto cartridge was by the FBI. After the 1986 FBI Miami shootout where 2 FBI agents were killed and 5 wounded by 2 serial bank robbers. The agents were equipped with 38 Special caliber revolvers, S&W 459 9mm pistols and Remington 12 gauge shotguns. The agents were pinned down by fire from a Ruger Mini-14 rifle used by one of the suspects. Although the suspects were shot multiple times from the 38 Special revolvers they kept fighting and killing. The aftermath of that lead to the FBI researching a pistol caliber with more “stopping power”. The results were the Smith & Wesson 1076 chambered in 10mm. With all of the benefits of the high power cartridge, the pistol proved to have too much recoil and was hard to train agents on. The pistol and ammunition combination had a short life with the FBI. The result was the reduction in power of the 10mm which would become the .40 S&W caliber. In the end the caliber never really caught on in the industry. It found its place with hunters as a primary and secondary back up pistol. Some liked it for competition.

In 2015, SIG announced their first pistol chambered in the 10mm Automatic caliber. The new pistol debuted at the 2015 SHOT Show. This project is a difficult one to take on. Given the history of durability issues with 10mm pistols SIG had to make it stronger and more durable than the competition. The P220 was the most logical platform. The larger frame plus the single column magazine were a great starting point. Within 6 months they had their pistol. The new pistol is made in the Exeter, New Hampshire factory. SIG offers the pistol in three different configurations as of this writing. The Match Elite Reverse Two-Tone which has a stainless steel frame with a black Nitron® coated slide, P220 Stainless Elite which is a complete stainless steel pistol and the P220 Stainless Elite Nitron® which is completely black. The last is the P220 Hunt Ready which is Kryptek® Banshee color. The weight of the pistol is 39.1 ounces. Overall length is 5.5 inches and overall width of 1.5 inches. The barrel length is 5 inches with a sight radius of 6.8 inches. The single column magazine holds 8 rounds of 10mm Auto ammunition.

Starting with the frame, the frame is manufactured from block of 416 SST stainless steel. This is important with the use of the 10mm Auto caliber. The traditional P220 uses an alloy frame. This would just not hold up to the abuse of the potent cartridge. The underside of the frame in front of the trigger guard has a section of MIL-STD-1913 rail making it compatible with a flashlight or laser device. Like all of its predecessors, the pistol has no manual safety. The left side of the frame has a slide lock lever and magazine release button. The pistol is equipped with the traditional SIG de-cocking lever. The grip panels are an extremely comfortable and sharp looking Black G-10 Piranha grip. Even with my large hands the pistol was comfortable and the gripping surface all around the grip gave a solid no-slip feel. With the exception of the locking insert, all of the internal parts are interchangeable in the frame with P220 45 Auto caliber components. The single action pull of the test and evaluation pistol were 5 pounds single action and 11.5 pounds double action. The double action felt heavy but it was easy to fire accurate shots once I got use to it.

The slide is manufactured from 416 SST stainless steel as well. The slide is offered in raw stainless steel, black Nitron® as well as the Kryptek® Banshee color. Most of the internal components of the frame are interchangeable with the P220 chambered in 45 Auto but the extractor, locking insert (Feed ramp is part of the locking insert which is the reason it had to be changed). The slide, like all of its predecessors, is equipped with a passive firing pin block safety. This is perhaps the one most important feature one can have on a pistol. This is a spring loaded plunger that blocks the firing pin from any forward movement. The only way the firing pin can move is to have the safety lever push it up and disengage it. The only way the safety lever disengages the firing pin safety is if the trigger is pulled all the way to the rear. As the trigger is pulled to the rear, just prior to the trigger bar releasing the hammer the trigger safety moves upward pushing the firing pin block out of the way. This prevents unintentional discharges from the pistol being dropped. There are gripping grooves both on the rear of the slide as well as the front. The pistol comes standard with SIGLITE® Night Sights.

The barrels is made of carbon steel coated in black Nitron®. The barrel is 5 inches long. The recoil spring should be changed out every 2500 rounds.

With the Buffalo Bore 200gr full metal jacket ammunition, the pistol shot about 1 3/4 inches at 25 yards. The gun certainly shot better than this author. All ammunition tested in this pistol shot right in this same area. This included the Buffalo Bore 220gr hard cast projectiles.

According to SIG, they expect the service life of the pistol to be approximately 10,000 rounds. They have tested several pistols to and above 10,000 rounds. This is a lot of rounds considering the wear and tear this cartridge puts on the gun. The test and evaluation pistol was well made, just what you would come to expect from SIG. It came with two magazines. The pistol was tested with a variety of rounds. These included 175gr Hornady Critical Defense, Hornady 155 and 180gr XTP, SIG V-Crown 180gr JHP, Double Tap 200gr FMJ, Buffalo Bore 220gr lead and 200gr FMJ and Federal American Eagle 180gr FMJ. In all, more than 300 rounds were fired through the pistol with no malfunction of any sort. Accuracy was excellent. The best group was achieved with Buffalo Bore 200gr FMJ with just over an inch at 15 yards off hand. But all the ammunition fired was just about the same. The pistol was not sensitive to ammunition at all. I am sure if the pistol was put in a vice, groups would have been tighter. But standing in the hot Texas sun, I was quite pleased with the results off hand.

The 10mm cartridge is mainstream now. Ammunition is made by all of the major manufacturers. There are several companies who are well known for their 10mm loadings. Word to the wise, be very careful with some of the hotter loads, they may meet but they also exceed SAAMI specifications. Target ammunition is not overly expensive. Particularly Federal American Eagle and Remington UMC. Some of the other excellent loads you would want to contact the manufacturers directly such as Buffalo Bore and Double Tap to see where they have stocking dealers. The 10mm Auto cartridge is an excellent choice for a hunting handgun for medium game. It is also an excellent choice for a backup gun when hunting large dangerous game. The SIG pistol has the range and accuracy to do the job. As far as a self defense gun, if the shooter is well trained and practiced in handling it, the P220 will be an excellent self defense pistol as well. The FBI spent a lot of money to find out this caliber is not good for everyone. But for those who train with it and get comfortable with it, there is no reason why you cannot carry it for personal protection. The P220 has all the features you would want for a defense firearms as it has been carried in various calibers by military, LE and security personnel for many years in some pretty terrible places!