SIG P320 M17 ASP Review

With its many innovations and usability as a personal defense trainer, the SIG P320 M17 ASP offers real benefits.

SIG P320 M17 ASP Review

Since 2014, SIG Sauer has drawn on the popularity of their centerfire firearms to create a rich portfolio of air-­gun replicas. These include the MCX, MPX, P226, P320, as well as several M1911 models. All share original-­model dimensions meaning that they are not toy-­like versions of the originals. They are structurally sound air guns with an authentic look and feel. The latest introduction, the SIG P320 M17 ASP (Advanced Sport Pellet), shows that they are dedicated to innovating the air-­gun market by making them serious training tools.

SIG Sauer P320 M17 ASP
The slide’s ejection port is another detail that enhances the air pistol’s authenticity.

The M17 ASP was first modeled after the civilian version of the SIG P320 M17, a similar pistol adopted by the U.S. Army, but with a few differences. Glancing at the M17 ASP, however, it’s easy to confuse it with the centerfire M17. The polymer frame, steel slide, ambidextrous controls, optic-­cut cover, ejection port and takedown lever all look familiar.

SIG Sauer P320 M17 ASP
An accessory rail means you can train with the same light and/or laser that would be mounted on a centerfire.

The M17 ASP also includes fixed sights and a rail for a light or laser. The only visual clues about its air power is the tiny barrel nested an inch inside the larger barrel-­like shroud, and the small “.177 CAL. (4.5mm)” mark molded on the left side of the frame. Boldly printed at the top of the M17 ASP packaging box are the words “Authentic weight, balance, and handling.” The M17 ASP checks off all three attributes. It weighs 34 ounces and is top and front heavy, just like you’d feel while handling the centerfire counterpart. It’s heft, balance and materials will have you dropping the magazine or pulling back the slide to check its state of readiness.

SIG Sauer P320 M17 ASP
The P320-M17 includes a fixed, three-dot white sight; the rear on an optic plate; slide-lock lever; thumb safety; and a disassembly lever.

The M17 ASP is a blowback-­operated, semiautomatic air pistol with a rifled, steel-­barrel chambered in .177. It’s powered by a single 12-­gram CO2 cartridge. Full blowback air guns work by directing some of its CO2 pressure to cycle the slide; The slide performs no other function and is meant only to simulate the mechanics of a semi­automatic, centerfire pistol.

With or without the slide action, an air gun produces a recoil force that is lighter than a semiauto .22 LR pistol. Still, there’s enough oomph to make you tighten your grip and bear down on shooting fundamentals. If you get too relaxed when shooting an air gun, you’ll likely miss the shot.

SIG Sauer P320 M17 ASP
The ASP caddy resembles the M17’s 21-round mag until it is removed. It houses 20 .177 pellets and a single CO2 cartridge.

What makes the M17 ASP stand out from the rest of SIG Sauer’s air-­pistol pellet line is the introduction of the single-­magazine caddy. The caddy houses both the CO2 cartridge and SIG Sauer’s patented belt-­fed magazine. The all-­in-­one design is a welcome departure from the P226 and P320 replicas, which feature grips with two separate compartments for the magazine and CO2 cartridge; Each have to be removed independently of each other.

The big advantage to a single magazine is that it’s closer in function and size to a centerfire magazine. The single magazine permits use of the same grip and reloading technique as a centerfire pistol. The slide doesn’t lock back on the last round, but the sound of the compressed air rushing through the barrel, sans pellet, is a distinct sound that lets you know when it’s time to reload.

What makes the M17 ASP even better is the magazine housing. It incorporates a patented cam-­lever design that seats and releases the CO2 cartridge. This can be done with the pull or push of a lever. There are no tools or wing nuts required to turn to seat the cartridge. To install a fresh cartridge, open the lever fully, drop in a CO2 cartridge and push the lever flush against the magazine.

SIG Sauer P320 M17 ASP
A single compartment within the grip houses SIG Sauer’s innovative true-drop magazine used to carry the CO2 cartridge and pellet magazine. The seals within the action’s gas system are effective at preventing leaks.

SIG P320 M17 ASP Magazine 

Many semiauto ­pellet air pistols use an eight-­round rotary magazine, or a double-­ended eight-­round magazine. The M17 APS benefits from SIG Sauer’s patented 20-­round belt-­fed magazine. The belt rides freely inside the magazine and is simple to load. The removable belt-­fed magazine seats at the front of the magazine housing and is freed with the push of a button. You don’t have to worry about the air loss when reloading; It’s minimal.

SIG Sauer P320 M17 ASP
The 20-round belt-fed magazine is easy to preload and it functioned flawlessly. It is inserted into the grip through the bottom in a similar manner as inserting a centerfire magazine. Similarly, the magazine release button allows it to be removed.

At this price point, the M17 ASP magazine wasn’t designed to take harsh impacts, and you should be careful not to deform the nipple or introduce dirt into the seal. If you start dropping mags on the ground, G&A recommends practicing over a lawn or carpet, and not concrete or dirt.

Pellet Choices 

Choosing a pellet for an air gun is similar to choosing ammunition for a firearm; You’ll have to shoot several pellet types to determine which shoots best for your task.

A pellet you’ll want to avoid in the M17 ASP is the pointed-­pellet type. Pointed pellets may not fit in the magazine and could end up jammed between the valve and chamber. To minimize jamming issues, spin the belt in the tray to ensure it moves freely after loading pellets into the belt-­fed magazine


The power plant of the pellet pistol is a 12-­gram liquid CO2 cartridge. One of the unique features of a CO2 cartridge is that it will maintain its pressure until the liquid CO2 has been depleted. In contrast, a high-­pressure air tank, like a pre­charged pneumatic, will lose pressure with each shot. This means that if you’re starting with a fresh CO2 cartridge, the average velocity and extreme spread of 10 shots will be roughly the same as 30 shots. Since the pressure in a CO2 cartridge is affected by temperature, expect to see fluctuations in the velocity as the cartridge cools down and warms up.

SIG P320 M17 ASP Trigger 

SIG Sauer P320 M17 ASP
The crescent-shaped hammer and brass head of the timing valve work similarly to a hammer that strikes a revolver’s transfer bar.

The M17 ASP sports a double-­action-­only trigger that feels similar to the striker-­fired P320 M17 centerfire. However, the M17 ASP’s inner workings are more like a revolver than a striker-­fired pistol. The trigger performs three functions: cocking the hammer, releasing the hammer, and rotating a pellet to the top of the belt-­fed magazine. Since this is an air gun, the hammer strikes a valve, which opens briefly to release a burst of pressurized gas that then pushes the pellet down the rifled barrel.

SIG Sauer P320 M17 ASP
The so-called “firing” mechanism of the air pistol is located under the slide. When the hammer strikes the firing pin, it opens the timing valve and releases a burst of CO2 gas.

The Small Things

We love when engineers pay attention to the details because it shows they’ve been given the latitude to make the very best product possible. Several details on the M17 ASP show that SIG Sauer’s engineers did sweat the small stuff. One example is the seal that the cartridge’s nipple presses against. This seal prevents air from leaking when it’s seated into position. Another example is the takedown lever which lets you fieldstrip the M17 ASP for cleaning. And then there’s the guiderod assembly, which looks similar to a handgunner. These details are a design departure from SIG Sauer’s older P226 and other P320 air pistols that use a recoil spring around the barrel shroud to manage the slide’s reciprocation.

SIG Sauer P320 M17 ASP
The M17 ASP fieldstrips are somewhat similar to the centerfire M17, including the removal of the barrel and recoil-spring assembly.

Vice president and­ general manager of SIG Sauer’s Air Gun Division, Joe Houston, said, “I told my team that they should have no preconceived notions of what is possible.”

We can easily see Houston’s vision in the M17 ASP. It’s the first true-­drop magazine, CO2 cartridge patented cam-­lever design and belt-­fed magazine. The M17 exudes innovations, which makes for a better shooting experience.

SIG P320 M17 ASP Performance 

Since the M17 ASP mimics the weight, feel and controls of the centerfire original, it has great promise to becoming a legitimate training tool for the days when you can’t get to the range. To test its efficacy as a training tool, G&A’s staff ran a standard accuracy test with three different pellets, and chose the best performer to see how many consistent shots could be obtained from using one CO2 cartridge.

H&N Baracuda Hunter Extreme Hollowpoint 9.5, Beeman 7.5 grain, and SIG Sauer’s Match Ballistic Alloy 5.3-­grain pellets were used. Targets were placed at 11 yards. The SIG Sauer Match Ballistic Alloy 5.3-­grain pellets were the fastest-­flying pellets by 70 feet per second (fps), and produced the smallest group. They were also the only pellets to reach the same elevation as the point of aim (POA), albeit they grouped 1.6 inches to the right. The center of the Beeman group was 13/4 inches lower than the POA, and 1.2 inches to the right. The H&N pellets were the heaviest and dropped 2.8 inches lower than POA. For self-­defense training, the M17 is sufficiently accurate to place shots in the thoracic cavity of a humanoid target.

Since the SIG Sauer pellets shot the best, we chose them for the consistency test and tracked the velocity of each shot with a chronograph. Seventy-­degree temperatures favored high velocities, so we expected the first shots to come out fast and then slow as the CO2 cartridge cooled. The first 10 shots averaged 391.1 fps with shot number one coming out at 439.3 fps. The next 20 shots averaged 374.5 fps, but were still hitting within the expected group sizes. Shots 31 through ­40 averaged 367.4 fps, and accuracy was still on point. Shots 41 through ­50 slowed to an average of 341.3 fps, but not one pellet dropped below the previous 40 pellets. Shot 50 was 301.3 fps and marked the first time a pellet fell outside of the group — 2 inches lower, which is unusual for this pellet. The rest of the shots showed a rapid decline in velocity. The test was stopped after 56 shots when the pistol whimpered as it threw a pellet.

SIG Sauer P320 M17 ASP
Notes: Accuracy is the average of five, five-shot groups fired from 11 yards benched on a sandbag rest. Velocity is the average of five shots fired using a Shooting Chrony Beta Master Chronograph placed 5 feet in front of the muzzle.

Fifty consistent shots out of one CO2 cartridge makes the M17 ASP an excellent training tool. It offers enough continuous shots to help with practice, and sufficient accuracy to consistently place shots on target. If the rear sight were adjustable, this air pistol would earn our highest recommendation.

The Takeaway 

When referring to the centerfire P320 and M17 pistols, G&A avoids using the phrase “real gun” because it undermines the stand-­alone value of air guns, especially one as good as the SIG P320 M17 ASP. The M17 ASP operates closer to its centerfire counterpart. Owners of the centerfire P320 and M17 should consider purchasing one of these as a training alternative. Unlike dry-­fire practice, you hear, feel and see the results of your shots downrange. With its many innovations and usability as a personal defense trainer, the M17 ASP offers real benefits. 

SIG P320 M17 ASP Specs

  • Type: Blowback, semiautomatic
  • Powerplant: CO2, 12 gram
  • Caliber: .177
  • Capacity: 20 rds. (pellets)
  • Barrel: 4.70 in.
  • Overall Length: 8 in.
  • Weight: 2 lbs. 15 oz.
  • Sights: Fixed, 3-dot sights
  • Safety: Lever
  • Finish: Coyote
  • Trigger: 6 lbs., 8 oz.
  • MSRP: $130
  • Manufacturer: SIG Sauer, 603-610-3000, 

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