SIG Sauer P322 .22 LR Pistol Boasts 20-Round Capacity

Billed as “The Most Advanced, Highest-Capacity .22 Pistol In Its Class,” the sleek new petite P322 from SIG Sauer's is about as cool as .22 LR sidearms come, complete with optic and suppressor readiness.

September 05, 2023 By Joseph von Benedikt

The new P322 has a magazine capacity of 20 rounds, which is unprecedented in the world of semiautomatic .22 LR pistols. It’s optic-ready, so you can swap out the rear sight plate for a red dot. And it’s suppressor-compatible and comes with the threaded mounting adapter.

Prime Features

The P322 also has a lot of additional bells and whistles. Every pistol comes with an extra trigger shoe, so you can switch between a straight trigger and a curved trigger. The sights are fiber optic and fully adjustable.

The fire controls are classic in location and operation, yet they’re cutting edge, too. In addition to the mirror-image, ambidextrous slide lock levers and thumb safeties, the magazine release button is reversible.

The size is halfway between SIG SAUER’s super-popular P365 XL in 9mm and the full-size P320. In a word, perfect. It’s large enough to provide a comfortable, full grasp in the hands, and the sight radius is long enough for accurate shooting. Incredibly, the P322 weighs just 17 ounces. That’s light!

The pistol comes with two polymer magazines, and each is rated to hold 20 rounds. As far as I can determine, that’s best-in-class capacity for a polymer-framed semiautomatic .22 LR pistol. That, combined with the featherweight heft and the fiber-optic sights, makes the P322 a prime choice as a trail gun.

SIG Sauer P322 .22 LR autoloader pistol with curved trigger shoe. — Each P322 comes with two trigger shoes. Installed is a flat trigger shoe, but it’s easily switched for the curved version if the customer prefers.

Pair a P322 with a lightweight suppressor and a high-octane weapon light or, if your eyes prefer it, a red-dot sight, and you’ll have one capable backcountry pistol. You’ll never know it’s there until you want it. And whether you’re running a long trapline or using it as a grouse-getter while bowhunting for elk, you’ll have a prime tool for the task at hand.

Let’s unpack the P322’s features more completely, starting with the operating mechanism.

Unlike the polymer-framed centerfire pistols it looks like, the P322 has a fixed barrel. That’s right; the barrel is mounted as part of the steel frame contained inside the polymer grip. Some experts think a fixed-barrel pistol has more accuracy potential than designs with tilting-barrel lockups. I’m not one of them—I’ve seen some Model 1911s shoot spectacularly well—but it’s a fun theory to consider. To be sure, it doesn’t hurt accuracy.

Like most .22 rimfire semiauto pistols, function is via blowback design. Energy is harnessed from the cartridge when it fires, pushing the slide rearward. This cocks the hammer (or striker), ejects the empty cartridge case, and loads the recoil spring. That spring then thrusts the slide forward, picking up a fresh cartridge from the magazine and chambering it.

SIG Sauer P322 .22 LR Autoloader Showing Captive Recoil Spring Held in Place by Muzzle Threat Cap — The new P322 pistol has a 4.0-inch fixed barrel with a captive recoil spring that is held in place by the muzzle’s thread cap.

Because the barrel is fixed, there are a few unique handling features to the P322 that are specific to disassembly and to mounting a suppressor.

To disassemble, drop the magazine and lock the slide rearward. Rotate the disassembly lever a quarter-turn counterclockwise, until it’s pointing up. Pull the slide rearward, and then lift up on it, away from the frame. It will separate an inch or so from the frame at the rear. Allow the slide assembly to move forward off the barrel, impelled by the captive recoil spring.

That’s about it. You can perform most maintenance on the P322 in this stage, including cleaning the barrel. If you wish, you can remove the recoil spring by unscrewing the thread protector and spring washer at the muzzle.

As for the rear sight, it’s incorporated into the removable polymer plate where a red-dot sight can mount. Fiber-optic inserts are set into the serrated face of the rear sight on each side of the square rear notch. As an aside, SIG SAUER’s ROMEOZero red-dot sight mounts directly to the pistol without need of any adapters. (For more about this fine optic, see Joel Hutchcroft’s Quick Shot on page 66.)

Vertical sight adjustment is achieved via two screws, one on each side of the sight. Initially, I found them a bit confusing, because they’re in the same sort of position as windage adjustment screws on traditional metal rear sights. Thankfully, they’re marked with a “U” and a tiny arrow, indicating which direction moves point of impact up.

Horizontal adjustment is simpler. Just loosen the tiny setscrew in the center of the rear sight notch (using the included hex wrench), push the sight gently in whatever direction is needed, and snug down the screw.

Aesthetic, angled flats are milled down the length of the lightweight alloy-metal slide. Grasping grooves provide a sure, non-slip grip front and rear.

Let’s move on to the polymer grip “frame” and the serial-numbered steel actual frame contained inside. The grip is well textured with stippled panels on each side and on the frontstrap and backstrap. The 20-round magazines fit nearly flush with the bottom of the grip and are easy to insert thanks to a generously beveled magazine well.

SIG Sauer P322 .22 LR Striated Front Sight with Green Fiber-Optic Insert — The striated front sight has a high visibility green fiber-optic insert. The sight appears to be polymer, but it is very robust.

A high undercut at the rear of the trigger guard helps shooters achieve a high, recoil-controlling grip. Likewise, the upper rear of the grip is profiled for a high grasp. Not that the P322 kicks much, but achieving a correct grip in practice builds good habits that transfer over when shooting more powerful centerfire semiautomatic pistols.

A comfortable rearward frame extension prevents slide bite to the web of the thumb. And a section of rail in front of the trigger guard makes mounting a weapon light or laser very easy.

Both the slide lock and the thumb safety have texturing. They’re low profile to minimize snagging on clothing but easy and sure to access and operate.

SIG Sauer P322 .22 LR Autoloader Pistol Fully Adjustable Rear Sight — The fully adjustable rear sight has two fiber-optic dots and is incorporated into a plate atop the rear of the slide. Installing a red-dot optic is as simple as swapping out the rear sight plate for a SIG Sauer ROMEOZero optic.

Prime Performance

Excited to fire the svelte polymer-framed .22, I gathered five different factory loads of varying manufacture and with differing bullet weights and profiles and set up to shoot three consecutive five-shot groups for average with each different load at a distance of 25 yards.

SIG SAUER includes a magazine loader assist tool, which engages with the pull-down tabs on each side of the follower and makes it easy to draw the follower down and drop cartridges into the magazine. I cheerfully piled both 20-round mags full, noting with some surprise that I could only get 19 cartridges in each. More on that in a minute.

Right out of the gate, I experienced a dismaying series of malfunctions. Rounds were nosediving and hanging up on the feedramp incorporated into the front of the polymer magazines. After removing the magazine and shaking the rounds free and up to the feed lips, those rounds would sometimes stovepipe when I dropped the slide, glancing off the feedramp and pointing skyward as the slide went home.

Not good, I thought and figured I had a pair of dodgy magazines.

Thankfully, a message to Michael Marotte, my contact at SIG SAUER, brought much-needed enlightenment: P322 magazines must be loaded properly to run properly. And, yes, there is a correct process.

SIG Sauer P322 pistol magwell with two mags and accompanying mag loader — Two 20-round polymer magazines and a magazine loader come with each P322 pistol. Note the generously beveled magazine well, which makes fast, sure reloads easy.

Rather than pulling the follower down and piling rounds in, as I did, Marotte instructed me to pull gently down on the follower tabs, just enough to ease the process of pressing each cartridge down through the feed lips and sliding it rearward into place. There must be upward pressure from the follower as you do so. This forces each .22 LR cartridge to align properly inside the double-stack magazine.

Sure enough, when I followed Marotte’s guidance, the magazines accepted 20 rounds and ran flawlessly.

At first, I felt a bit put off by the fact that the magazines aren’t fumbleproof. An inexperienced shooter or a kid could experience frustration—as I initially did—because their pistol seemed unreliable. A bit of reflection brought me around. Shoehorning 20 rounds into a compact, lightweight .22 LR semiauto pistol is not an easy feat, and loading it carefully is an easy price to pay for such firepower.

According to Marotte, a short educational video on the loading process is in the works. By the time you read this, it will likely be available on the company’s website.

Correct loading mastered, I pressed on with my testing. Idaho’s weather in springtime is capricious, and a stinging snowstorm blew in, accompanied by driving 20-mph winds. Still, the little P322 produced good groups.

Full results are listed in the accompanying chart. Three of the five loads tested produced averages of less than 1.5 inches at 25 yards. Considering the conditions, that’s excellent accuracy.

Point of impact was a bit high and left. A turn with the included hex wrench solved that, and soon the little P322 put bullets directly on point of aim.

One of the more impressive loads I tested is Federal’s Punch .22 LR flatnose load with its 29-grain, hardened bullet. Muzzle velocity was more than 1,200 fps, which is darned fast for a .22 handgun. Accuracy was reasonably good, averaging less than 2 inches at 25 yards. I’m not a proponent of packing a .22 rimfire for personal protection, but if you’re determined to do so, the 20-plus-1 capacity of the SIG SAUER P322 makes it a good choice, and pairing it with the speedy, hardened Punch flatnose load, which is designed for straight-line penetration and for imparting energy, makes good sense.

Author Joseph von Benedikt shooting the SIG Sauer P322 pistol — Lightweight and compact yet handfilling, ergonomic, and well-balanced for excellent shootability, Joseph says SIG Sauer’s P322 is the perfect size.

Clinical accuracy testing completed, I stepped away from the bench and fired casually—running informal drills, shooting left-handed, and so forth—to get a better feel for the P322 pistol. My son Henry (age seven) joined me, and he drove shot after shot into an 8-inch-round length of firewood in front of the berm.

Not only is the 17-ounce weight of the P322 easy for him to hold up and aim steadily, but also the little pistol has a pretty decent trigger. Although it’s a tad spongy, like most polymer-frame pistols, it’s not heavy, which certainly helped Henry get shots off cleanly.

Finally, I loaded up the family and drove to a friend’s backyard range, where he has racks of steel targets set up for handgun shooting. Considering the expense of ammo these days, we went through a painful (but delightful) amount of .22 cartridges pinging steel. Through it all, the P322 ran like a top.

At the time of this writing, holsters aren’t yet available from the various holstermakers, but that is sure to change. Meanwhile, SIG SAUER offers an ambidextrous IWB/OWB holster for $30. It’s Kydex, features an adjustable retention screw, and can be packed right side or left side and inside or outside the belt.

The new SIG SAUER P322 .22 LR pistol is loaded with premium features, is extremely ergonomic and shootable, is more accurate than expected, and has a wonderful combination of practical capability and panache. It is definitely a prime choice.

SIG Sauer P322 Specifications

Manufacturer: SIG Sauer, sigsauer.com
Type: Blowback-operated autoloader
Caliber: .22 LR
Magazine Capacity: 20 rounds
Barrel: 4.0 in.
Overall Length: 7.0 in.
Width: 1.4 in.
Height: 5.5 in.
Weight, Empty: 17.1 oz.
Grips: Integral to polymer frame
Finish: Black hard-coat anodized
Sights: Fully adjustable fiber-optic rear, fiber-optic front, slide is milled for optic mounting
Trigger: 4.75-lb. pull (as tested)
Safety: Ambidextrous manual thumb safety
MSRP: $695.99