Sig Sauer P320RX 9x19mm Pistol

By the Guns and Shooting Online Staff

Sig Sauer P320RX
Illustration courtesy of SIGARMS.

In January 2017, Sig Sauer announced they had won the US Army contract for its new modular handgun system. (see The Column, No. 109 for details.) The two finalists for the military contract were the Glock G17/G19 and the Sig P320. In Army service, the P320 will be known as the M17.

SIG states, "The P320 is the first modular pistol with interchangeable grip modules that can also be adjusted in frame size and caliber by the operator. All pistols will be produced at the SIG SAUER facilities in New Hampshire."

The P320 was introduced to the civilian market in 2014. It is a polymer framed, striker fired, short recoil operated, autoloading pistol intended to compete with the Glock G17 and similar pistols.

There is no manual safety, nor is one needed. Like a double action revolver or a Glock Safe Action, which the P320 emulates, the P320 action is inherently safe. The only manual controls, aside from the trigger, are an ambidextrous magazine release and a takedown lever. Internally, there is a striker safety and a disconnect safety. There is no trigger safety and also no second strike capability.

For 2017, there are 10 P320 variations including full size, compact and sub-compact models. Available calibers include 9mm Luger, .357 SIG, .40 S&W and .45 ACP.

For this review we chose the full size P320RX in 9x19mm, which is supplied with a small, slide mounted reflex sight. This is the most expensive P320 variation ($1040 MSRP), but we thought it the most interesting.

Like other Sig pistols, the P320 is supplied in a useful and durable, hinged plastic case with a fitted, foam padded interior. Inside the case is the pistol, two magazines, gun lock, an owner's manual and other paperwork.

P320RX Advertised Features

  • Sig ROMEO1 red dot reflex sight factory mounted on slide and zeroed to match the SigLite iron sights.
  • Striker-fired, interchangeable trigger group.
  • Smooth, crisp trigger.
  • Three point takedown.
  • Unmatched modularity.
  • Full size grip frame and slide.
  • Safety features include a striker safety and disconnect safety.

Sig ROMEO1 Sight Features

  • Molded glass aspheric lens with high performance coatings.
  • 3 MOA red dot.
  • Manual illumination controls remember your last setting.
  • Multiple brightness settings.
  • Motion activated illumination.
  • The CR1632 battery is top-loading, allowing for quick battery replacement without having to remove the sight from the firearm.
  • Aircraft grade CNC magnesium housing.
  • Water and fog proof (IPX-7 rated for complete immersion to 1 meter).

P320RX Specifications

  • SKU: 320F-9-BSS-RX
  • Caliber: 9mm Luger
  • Magazine capacity: 17 rounds
  • Action: Semi-auto, short recoil operation
  • Frame size: Full
  • Grip type: Modular polymer
  • Frame material: Stainless steel
  • Slide material: Stainless steel
  • Slide finish: Nitron
  • Barrel material: Carbon steel
  • Barrel length: 4.7 in.
  • Accessory rail: M1913
  • Trigger: Striker
  • Trigger type: Standard
  • Trigger pull: 6.5 lb. (7 to 8 lbs. measured)
  • Iron sights: SigLite tritium night sights
  • Overall length: 8 in.
  • Overall width: 1.4 in.
  • Height: 6.3 in.
  • Weight: 29.5 oz. (empty)
  • Made in: USA
  • 2017 MSRP: $1040

As the above features and specifications indicate, the P320RX is an interesting full size pistol, ready for service or home defense applications right out of the box. For home defense use, the only accessory we can suggest is a projected laser sight to mount under the barrel on the integral M1913 accessory rail.

Examining the outside of the P320 reveals a rather tall slide with wide, easy to grip serrations front and rear, which make the slide easy to rack. The accessory rail has five slots, which allows better than average latitude for mounting accessories, such as a laser sight or light.

The front of the trigger guard is squared for a supporting hand index finger and the rear of the trigger guard is slightly under-cut for the middle finger of the shooting hand. There is no hammer to worry about biting the web of the shooting hand, but a medium size beavertail keeps the shooting hand from sliding up the grip. Small, but functional, rests for the thumb of the shooting hand are present on both sides of the polymer grip frame.

The P320 is ambidextrous. There is a small, Glock like, sheet metal slide release on both sides of the frame and the magazine release can be switched from one side of the frame to the other. The take-down lever is mounted on the left side of the frame in the traditional location.

The grip is oval in shape with fine stippling patterns on both sides, as well as the front and back. It is a very comfortable grip in medium to large size hands. There is a lanyard hole at the bottom rear of the grip.

Unlike several modern autoloading pistols, the P320 does not use interchangeable back straps to alter the grip size. Instead, the entire grip module (the polymer frame) of the pistol is replaced.

Guns and Shooting Online staff members Chuck Hawks, Rocky Hays, Jim Fleck and Kathy Hays participated in this review. Chuck and Rocky found the magazine release very easy to use. Jim and Kathy found their grip on the pistol had to be substantially altered to hit the release button with the thumb of the shooting hand.

While the P320 has a comfortable, oval shaped handle, it has an upright, 1911 grip angle. All of our staff members prefer the more slanted (Luger) grip angle of Glock pistols for instinctive pointing.

The P320 double stack magazines hold 17 9x19mm cartridges. The magazines are made in Italy with steel bodies, a removable polymer bottom plate and a polymer cartridge follower. There are three view holes in the right side of the magazine, showing the 5th, 10th and 17th cartridges.

The top of the magazine is tapered to reliably feed one cartridge at a time and this makes the magazine easy to insert into the bottom of the grip. The magazine clicks positively into the grip and empty magazines drop free of the grip when the release button is depressed, assisted by a push from the magazine spring.

A small, trapezoid shaped, polymer tab on the magazine follower activates the slide lock to hold the slide open for the last shot. This can catch on the upper edge of the magazine body when the magazine is empty, making loading the first cartridge more difficult than necessary. After the first is loaded, subsequent cartridges load normally for a high capacity magazine.

While the P320 is conceptually similarly to a Glock Safe Action, the internal parts are different and more complicated. When you first remove the slide and look down into the receiver the parts look rather similar to a Glock, but they are not, although they achieve the same operations.

In the P320, all the operating parts, including the steel slide rails, are contained in the "frame assembly." It is the frame assembly that bears the gun's serial number. The "grip module" (the entire polymer lower) is removable and replaceable.

The smooth steel trigger is wide and curved. It is comfortable to the finger, although Chuck thought it had a bit too much curve.

The trigger pull is a problem. It is much heavier than specified, averaging about 7.5 pounds per our RCBS pull gauge. It is also inconsistent, varying anywhere between seven and eight pounds from pull to pull. There is plenty of take-up before the serious pull starts, followed by some smooth creep before the striker is finally released. This is the worst trigger pull we can remember in a Sig Sauer pistol.

The P320RX comes supplied with SigLite fixed iron sights. These are excellent Patridge type sights with Tritium illumination for use at night. Both the front and rear sights are mounted in dovetails, so they can, with considerable difficulty, be moved laterally to adjust for windage. To adjust for elevation you have to replace either the front or rear sight, or both, with taller or shorter versions.

The SigLite rear sight is useable with the Romeo1 reflex sight in place and the SigLite front sight is visible through the reflex sights glass window. This means the iron sights can be use with the Romeo1 turned off, day or night. This is an excellent feature, as the shooter's eye must be on axis with the reflex to see the red dot. We found the easiest way to pick-up the reflex sight's red dot was to approximately align the iron sights and there it is, superimposed on the front sight blade.

Takedown for routine cleaning is straightforward. First, remove the magazine and make sure the chamber is empty. Then, lock the slide back. Rotate the takedown lever fully clockwise (past 90 degrees). Release the slide catch and slide the barrel/slide assembly forward off of the frame. That is all there is to it. No tools required and no loose parts.

Once field stripped, the pistol can be cleaned. No further disassembly is normally required.

The cleaning instructions in the owner's manual are very specific and too detailed to repeat here. You are supposed to clean the pistol after every use and every 500 rounds. SIG recommends using CLP for cleaning the barrel and internal parts and using CLP/LSA for lubrication, which is to be applied to specific places. There is a specific warning NOT to lubricate the striker or allow lubricant to flow into the striker channel of the slide.

The magazine is disassembled just like a Glock. Use a punch to depress the magazine floor plate insert and slide the floor plate forward off the magazine body.

Incidentally, the owner's manual also warns against using any parts or accessories not manufactured by Sig Sauer. Since the P320/M17 is the new US service pistol and aftermarket manufacturers are virtually certain to jump on the bandwagon, as they have with previous service pistols, we think Sig Sauer is going to have a tough time enforcing this edict.

Shooting the P320

We did our test shooting from a bench rest at the Izaak Walton outdoor range south of Eugene, Oregon. The late Spring weather was sunny with only a light, variable breeze and a high temperature of about 70 degrees F. Chuck, Rocky, Kathy and Jim handled the shooting for record.

We fired five-shot groups for record using four kinds of factory loaded ammunition. These included Winchester USA (white box) 115 grain FMJ, Speer 124 grain Gold Dot JHP, Sig Sauer Elite 124 grain FMJ and Sig Sauer Elite 147 grain FMJ. Sig Sauer graciously provided the two latter loads for this review.

As you might expect, the P320 performed well in the accuracy department compared to most other service autoloaders. The mean average group size for all loads was 2.57" and there were no malfunctions during testing.

Like most Sig pistols, the P320 has a rather tall slide and a high bore axis. With most of its weight up high, it is noticeably top heavy with an empty, or mostly empty, magazine. A high bore axis somewhat increases muzzle flip on recoil, although we have never found it to be a problem with other Sig pistols and did not with the P320, either.

All of our shooters complained bitterly about the P320's lousy trigger pull. The heavy and inconsistent let-off caused a higher than normal number of flyers. This is an accurate pistol, but a hard pistol to shoot accurately, because of the trigger.

The second most common complaint was the difficulty of getting the first round in the magazine. This is not a big deal at the range, but it would probably be disconcerting if you were trying to reload a magazine under combat pressure, such as during a fire fight.


We think the Sig Sauer P320RX is a good service pistol. The basic P320 won the Army competition to be the new M17 service pistol, so we expect lots of aftermarket goodies to become available in the next year or so. Based on need, parts to improve to the trigger pull will probably be among the first of these.

Note: The full length review of the Sig Sauer P320RX, including complete shooting results, is available to Members on the Product Reviews page.

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