Thanks to some truly clever engineering, the P320 from Sig Sauer can easily be transformed from a subcompact 9mm to a full-sized .45 ACP. How does it work?

A stainless steel chassis inside the frame houses the fire control system, slide stop and frame rails fore and aft. A window is cut into the right side of the polymer frame to allow the chassis’ serial number to be viewed. In essence, users can switch between four different frame sizes and three different slide lengths.

There are currently four P320 variants with accompanying slides and frames: Full Size, Carry, Compact and Subcompact. In addition to the difference in height, the grip modules are available in small, medium and large circumferences to accommodate different hand sizes.

Sig offers three slide/barrel units for the P320. The Full Size features a 4.7-inch barrel while the Carry and Compact slides feature a 3.9-inch barrel. The Subcompact slide sports a 3.6-inch barrel. Along with size options, the system allows for caliber conversions as well. All of the P320 sizes can be converted between 9mm, .40 S&W, .357 SIG and .45 ACP.

The P320 also offers several enhanced safety features that make it unique in its field. The internal striker safety prevents the striker from being released until the trigger is pulled. A disconnect safety prevents the pistol from firing if the slide is out of battery.

Finally, the Three-Point Takedown Safety System requires that the magazine be removed and the slide locked to the rear before the takedown lever can be rotated to the proper position. Sig is quick to note that the P320 does not require the trigger to be pulled before the pistol can be field-stripped. Recognizing the needs of the law enforcement community, Sig offers the options of a trigger safety toggle and a magazine disconnect safety.

On top of all of this, Sig’s engineers have worked hard to make the P320 as ergonomically friendly as possible. In addition to the four different frame modules, all P320 models feature an ambidextrous slide stop and a reversible magazine catch.

For more information, visit

Up Next

Non-Lethal Training: Marines Train Firsthand with OC Spray

During the non-lethal weapons training course, Marines took a shot of OC spray in...