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SIG P320 9mm Review

Is the SIG P320 9mm modular pistol the best polymer-frame high-capacity sidearm ever designed?

SIG P320 9mm Review

Currently, the SIG SAUER P320 is best known for two things.

First, a P320 variant dubbed the M17 won the incredibly prestigious U.S. military Modular Handgun System (MHS) contract. Second, it recently went through a social media blitz when an independent tester discovered that under certain conditions the pistol could discharge when dropped.

Like handguns by Glock, Smith & Wesson, FN, and others, the P320 passed standardized drop protocols, which designate height and angle of drop tests as well as impact surface. The tests that the P320 failed were non-protocol drops of increased heights and from improvised angles.

Interestingly, when the drop-test incident came to light, SIG was already rolling out a new, lighter-weight trigger improvement, and while it wasn’t actually engineered to correct drop-test anomalies, it did. Within weeks of the incident, all P320 pistols were shipping with the new trigger.

The P320/M17 family achieves beyond-par versatility by virtue of a serial-numbered chassis adaptable to any grip frame size and slide/barrel length or caliber (within reason—9mm Luger, .357 Sig, and .40 S&W all fit and function on the same chassis). No tools are required to perform the conversions, and swapping the parts is surprisingly easy.

Distilled to the basics, the P320 is a polymer-framed, high-capacity, striker-fired semiautomatic handgun. Unlike most, however, the “frame” is the serial-numbered chassis inside.

SIG P320 9mm Pistol Specs

Termed a “grip module,” the visible lower half of the P320 is made of fiberglass-reinforced polymer and features a sturdy accessory rail on the dustcover at its front (except on the subcompact version); stippled-type texture panels on each side of the handle as well as the frontstrap and backstrap; and a reversible magazine release. And it’s available in a variety of sizes.

Outstanding ergonomics are engineered into the grip module. The rear of the trigger guard curves up and is deeply undercut to allow a high, comfortable, recoil-controlling grip.

The fire controls are ambidextrous, either via side-swapping (the mag release) or because there is one permanently on each side (the slide lock). The U.S. military version features a manual thumb safety.

As for the slide assembly, it’s constructed of a high-strength stainless steel. Nicely sculpted with full-length bevels that crescendo toward the muzzle end, it possesses a simple elegance that is given a biting edge by the aggressive, radius-bottomed slide serrations front and rear.

Finished in ultra-durable Nitron, the slide and internals shrug off the most aggressive corrosion. Atop the slide are robust but low-profile three-dot sights (either high-contrast paint or SIGLITE night sights depending on the version) that feature an abrupt front face, enabling the user to rack the slide against a belt, steering wheel, or boot sole should one hand become disabled. Front sights are stamped with a tiny number to denote height and facilitate accurate sight changes should a point of impact correction be necessary. Windage is adjustable by drifting one or both sights in their dovetails.

Shooting Times Editor in Chief Joel Hutchcroft requested that I test-fire several different sizes of the P320 for this article, so I repaired to the range with three of the four common configurations (Full Size, Compact, and Subcompact), missing only the “carry” size, which is a full-size grip paired with a compact-length slide assembly.


SIG P320 9mm Accuracy Results
NOTES: Accuracy is the average of three, five-shot groups fired from a sandbag benchrest. Velocity is the average of five rounds measured 10 feet from the guns' muzzles.

On the day that I did my test-firing, the wind was unusually stiff. Accuracy testing in heavy wind is always interesting, and while I’m sure all three pistols would have posted better averages on a calm, bright day, each performed better than adequately. The full-size version proved excessively easy to shoot well, averaging less than 2.00-inch groups with 50 percent of the ammo tested. The Compact size also averaged less than 2.00 inches with its favorite of the four loads tested. And the Subcompact averaged less than 3.00 inches with three of the four loads. Reliability with all three was absolutely stellar, but then, that’s to be expected from a SIG pistol.

Due to the outstanding ergonomics, recoil is downright pleasant in the two bigger P320s, and while slightly zestier, it is still comfortable in the Subcompact. The iron sights are easy to resolve, and the triggers break cleanly.

Is SIG’s P320 modular pistol the best polymer-framed high-capacity sidearm ever designed? Rigorous testing by the U.S. military convinced them that it is. My limited experience with it suggests the military just might be right.

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