Introduction to different P320 Models

Sig Sauer P320 was first introduced in ​2014. It is based on the P250 model. The P250 was the first modular platform. However, P250 had a DAO trigger and a spurless hammer, making hard to compete with other similar polymer framed pistols. It was offered in 6 different calibers, ranging from .22 LR to .45 ACP.
P320 addressed the DAO trigger of it's older brother with a pretensioned Double Action Striker. It has brought the P320 a much wider popularity. Much was written and said about this particular gun - both in professional and technical reviews by leading experts and in basic home-made videos by enthusiasts, and there is no need for just another review. A small condensed summary of key features would be helpful at this point.Main Features:
Trigger Mechanism: Striker-fired, 5.5 pound trigger pull.
Safety: Standard models - no manual safety. Army version and some Civilian models have an external manual safety.
Grip Angle: perfect 17 degrees, which helps with natural point of aim and fast sight acquisition.
Disassembly:​ unlike most of the competitor guns, P320 does not require a trigger-press for disassembly. Disassembly and reassembly are easy
Different Calibers:
Sig Sauer P320 comes in 4 different calibers: 9mm (most popular), .40 S&W, .357 SIG and .45 ACP. An important note has to be made, that .45 ACP version is not interchangeable with other calibers, both FCU and Grip Module are different than the other calibers.
Different Sizes:
There are over 40 official configurations of P320. However, there are 3 basic sizes: Sub-Compact, Compact/Carry, and Full Size.
Sub-Compact is the shortest slide configuration, meant for concealed carry. The barrel length is just 3.6 inches. Magazine capacity is 12+1 in 9mm.
Compact/Carry are technically two different versions. The slides are identical and the barrel length is the same, 3.9 inches, but the difference is the grip module, which affects magazine capacity. Compact comes with 15-round 9mm magazine, while Carry has 17 rounds of 9mm in the accompanying magazines.
Full Size is the longest version, with a 4.7 inch barrel and 17-round magazines in 9mm.
Special Models:
Tacops - Two versions, Full and Carry, come with 21-round magazines. Carry comes standard with a threaded barrel.
RX - ​​this model comes with the optical sight installed, Sig's Romeo 5 and there are also two versions: Full and Compact.
M17, M17-Bravo - Civilian versions of the Army gun with the manual safety. Coyote PVD or Nitron black.
M17 Commemorative - a limited edition of 5,000 units that is the exact same weapon as what the Army gets.

Sig Sauer released an updated line of P320 - X-series. It is not to be confused with the Caliber X-change Kits, which are not X-series.
X-Carry - it is the updated Carry version that comes with lightened slide, X-Ray sights and updated grip module. The slide is pre-milled for the optic sight.
X-FIVE - a complete competition gun that is match ready out of the box. It is a full sized pistol with a 5 inch barrel, ported slide, fiber-optic front sight, adjustable rear side, removable steel magazine well, removable grip weight to better balance the longer pistol. It comes from the factory with 4 21-round magazines.
X-VTAC - a special edition that comes with a lightened FDE slide and is basically a full-size slide on a X-Carry grip. Barrel length is 4.7 inches.

Which model is right for you?
Does it have to be just one? The beauty of P320 platform is that you don't have to have just one model. You can have one pistol with different slides, grip modules and other options.