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Sig Sauer has been providing pistols and rifles to law enforcement agencies for decades. Sig Sauer P226 and P229 pistols are issued to thousands of U.S. officers, agents and soldiers throughout the country and abroad. Sig pistols are among the most ergonomic available, with proven track records of reliability, accuracy and longevity. Agencies that require pistols with decockers often choose Sigs. But it can take more time to train officers to operate pistols with manual safeties and decockers. Striker-fired pistols are popular with agencies, and they often feature interchangeable backstraps, so one pistol can be configured to fit a wide range of officers. Generally, striker-fired pistols are also more affordable and suffer no loss in reliability. Agencies dedicated to Sig Sauer, or those looking for something similar, had few choices. When it comes to rifles, being able to alter their configurations for assignment changes is huge, as it eliminates the need to purchase new rifles. Sig Sauer has listened and addressed these issues, introducing two weapons—the P320 pistol and SIG556xi carbine—that are perfectly suited to law enforcement and take modularity to new heights.

Modular SIG556xi

The standard SIG556xi handguard is made of polymer, has several cooling vents and can accept Magpul MOE accessory rails.
The standard SIG556xi handguard is made of polymer, has several cooling vents and can accept Magpul MOE accessory rails.

The SIG556 platform is proven, reliable and comfortable to shoot. Its folding stock allows for versatility that the AR platform has yet to achieve. I’ve assisted a few agencies with transitions from SIG551>s (or similar) to ARs, and ergonomics was the primary concern. Many officers preferred using the SIG551A1 or SIG556, but choices in forends and other accessories were lacking. Listening to requests from officers and armorers, Sig Sauer redesigned the SIG556 to accommodate those concerns. The resulting SIG556xi takes modularity to a new level.

“For the minimalist, the standard polymer handguard is great; you can add MOE rails for lights and other accessories or leave it smooth…”

The SIG556xi’s upper receiver is serialized, not the lower. SIG556xi lowers are configured to accept AR or AK magazines, and agencies can facilitate moves between select-fire and semi-auto variants more easily. Users can also swap out the barrel, as one platform accommodates various barrel lengths and calibers. An officer moving into a SWAT role can switch from a 16- to a 10-inch barrel—no new weapon is needed. That same officer can switch from 5.56mm NATO to 300 BLK with just a barrel swap. Want to use 7.62x39mm ammo? Simply change out the barrel and bolt, swap the Standard lower receiver with the “Russian” version and use AK-based magazines.

The barrels are nitride-treated and capped with Sig’s three-prong flash suppressors. The 5.56mm barrel has a 1-in-7-inch twist rate, while the 7.62x39mm has a 1-in-9.5-inch twist rate. A three-position gas block adjusts for adverse conditions and suppressor use.

The SIG556xi Standard comes with a Swiss-like folding stock similar to the one popular on the SIG551 and SIG556, though it features a removable polymer cheekrest. Users can swap this out for a tubular folding stock as well as a more traditional AR-style stock. Three different forends are available. For the minimalist, the standard polymer handguard is great; you can add MOE rails for lights and other accessories or leave it smooth. An aluminum tri-rail forend is also available as well as a super-lightweight carbon-fiber version. Making all of these changes is simple—no serious tools are needed, and they can be done in the field.

The rifle comes with a nice set of flip-up iron sights, one mil-spec aluminum magazine and a single-point sling. Add a couple of extra magazines and you are ready to go to work. The charging handle can be moved to either side in seconds. Both the magazine release and safety are ambidextrous. There is a bolt release on the left side that is easily accessible for magazine changes.

Striker-Fired P320

The P320 is a hammerless design that features a striker-fired system in its place. Note the SIGLITE night sights.
The P320 is a hammerless design that features a striker-fired system in its place. Note the SIGLITE night sights.

Sig Sauer is currently offering the P320 in 9mm, .40 S&W and .357 SIG, with .45 ACP coming later. The company built the P320 from the ground up based on requests from police and military personnel. Rather than provide a molded-in fire control system, Sig opted to make it removable using the P250 platform. To change the grip frame, turn the takedown lever, remove the slide and take out the serialized fire control module. This allows the same serialized fire control system to be placed in several grip frames. Frames are available in small, medium and large grip sizes. In essence, this kind of modularity could be huge for agency armorers, as it allows one weapon to stay with an officer throughout their career. Currently, Sig is offering both Full-Size and Compact models of the P320 with 4.7- and 3.9-inch barrels, respectively.

P320s can be ordered with safety configurations to meet most agency needs. The fire control system passes drop tests with or without a trigger-mounted safety toggle. Agencies that require trigger safeties can get them installed, while others can leave them off, providing a smooth, metal trigger. The trigger has a distinct reset, with little take-up and a crisp break at around 6 pounds. The P320 also has an ambidextrous slide release, and the mag release can be switched easily to either side. For those requiring a magazine disconnect safety (i.e., the pistol will not fire without a magazine inserted), that is also available. You can even get a thumb safety if your agency requires an external mechanical safety.

SIGLITE night sights come standard on the P320. A pronounced ledge on the rear sight facilitates unconventional reloads. The 17-round magazines are metal, and a cutout in the grip allows you to pull downward on a loaded magazine in case of a malfunction or to make sure it’s properly seated. A Picatinny rail molded into the dust cover accommodates lights and lasers.

There is no need to press the trigger to disassemble the pistol for cleaning. Remove the magazine and lock the slide back. Turn the takedown lever completely, and the slide comes right off. Repeat in reverse to reassemble the pistol. You cannot turn the takedown lever with a magazine in the pistol (loaded or not), making it one of the safest and easiest-to-maintain striker-fired pistols yet in my opinion.

Range Time

The SIG556xi’s reliability was as expected from this operating system—I experienced zero malfunctions.
The SIG556xi’s reliability was as expected from this operating system—I experienced zero malfunctions.

Sig Sauer sent me a first-production, 9mm Full-Size P320 and three 17-round magazines along with a 16-inch-barreled SIG556xi Standard in 5.56mm NATO. So far over 5,000 rounds have been fired through this P320. The pistol’s reliability to date has been flawless, with zero malfunctions using several ammunition types. The ejection pattern is amazingly consistent, and the SIGLITE sights are easy to see and as solid as a rock. The ergonomics are excellent—the P320 fits my hand better than most popular striker-fired pistols. My test P320 has a smooth trigger (no safety toggle) with a crisp, 6-pound pull. It feels closer to my P226 SAO’s than a typical striker-fired pistol. The slide release’s placement, like other Sigs, facilitates fast reloads, and you can access it easily with either hand without having to shift your grip.

“Put the P320 and SIG556xi together and you have a great setup with similar trigger feels, solid manufacturer support and proven reliability…”

The P320’s accuracy was excellent, with the best group coming from Black Hills’ 115-grain TAC-XP +P ammo at just over an inch. Comfortable to shoot using +P ammunition, the P320 fired everything accurately. In short, the pistol is versatile, modular beyond belief, and it feels and shoots like a hammer-fired pistol. It’s pretty hard to beat.

For testing the SIG556xi, I added Bushnell’s newest Elite Tactical CQTS 1x32mm red-dot sight. With a retail price at $350, it offers significant value—always critical to officers and agencies.

The SIG556xi’s reliability was as expected from this operating system—I experienced zero malfunctions. Most testing was completed using Lancer L7AWM magazines, although it functioned with both Gen 2 and Gen 3 PMAGs and aluminum mil-spec units. The carbine is a soft shooter that is easy to control. The trigger is a two-stage unit measuring at 7.5 pounds. The trigger is clean, predictable and pretty fast. The magazine release is easy to access with either hand. Accessing the safety required me to turn the rifle a bit—those with longer fingers may have better luck. It’s ambidextrous, so you can use your trigger finger if needed. Releasing the bolt from the left side is just like using an AR, and it’s just as fast.

The SIG556xi’s accuracy was also excellent. My best group, using Silver State Armory’s 64-grain PPT bonded ammo, measured 1 inch. This ammunition has proven accurate in several rifles and is perfectly suited for duty use, offering excellent ballistics. Everything else grouped into less than 1.5 inches. Throughout testing, the CQTS sight held its zero.

Final Thoughts

The P320 is available with a smooth-faced trigger (shown) or one with a trigger safety toggle. Either way, it will pass a drop test.
The P320 is available with a smooth-faced trigger (shown) or one with a trigger safety toggle. Either way, it will pass a drop test.

I was hard pressed to find any fault with the P320. Everyone who has handled this pistol likes it and loves shooting it. It has proven 100-percent reliable for over 5,000 rounds (and counting) with little to no cleaning, just some oiling. It is accurate, comfortable, and the trigger is excellent—rivaling hammer-fired pistols—with no annoying safety lever. For agencies, the modularity could be a real money-saver. If there is a shortcoming, it is the current lack of holsters, but time will take care of that.

Once all the options for modularity are available, the SIG556xi will prove incredibly advantageous for officers and agencies. Rifles are costly; the ability to change barrels, forends or stocks to suit SWAT, motorcycle or other units is huge—not only for cost, but also when it comes to time and convenience. With a proven operating system, solid ergonomics and unparalleled modularity, the SIG556xi is just about perfect for a police agency or officer. Put the P320 and SIG556xi together and you have a great setup with similar trigger feels, solid manufacturer support and proven reliability. It just does not get much better than that.

For more information, visit http://www.sigsauer.com or call 603-772-2302.

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