My P320 | The World of SIG’s Customization

January 4, 2023  
Categories: Guns

The P320 has had quite the life. It’s a relatively new firearm, but it’s already become the chosen sidearm of the United States military and tons of police forces. It’s a favorite in the hands of competition shooters, home defenders, and concealed carriers. Success comes from being reliable, available, and easy to shoot. Lots of striker-fired, polymer-frame pistols do that, but a big part of what made the P320 successful was the ability to be customized.

The P320 and Customization

The serialized portion of the P320 is what’s called the Fire Control Unit. The FCU is a chassis that holds all of the firearm’s internals and can be removed with the removal of a take-down pin. This allows a single serialized firearm part to be swapped between frames, slides, and calibers with ease. SIG started this with the SIG P250, but that DAO pistol wasn’t quite so successful. The P320 rivals the AR-15 parts selection.

My P320 – Inside and Out

The striker-fired P320 proved popular, and SIG went wild with it. They put their full weight behind the pistol, as did a rather receptive aftermarket. Today I’m going to detail my P320 and show the choices I made when constructing my own pistol and hopefully illustrate just how far down the rabbit hole you can go. Hopefully, it will help you decide if you want one.

P320 X Series Slide – Compact

I wanted a compact size that would allow for both an easily concealed firearm and a capable fighting weapon. The Compact slide size made it quite easy to do both and provides a 3.9-inch barrel. Of course, I went 9mm. SIG’s X series slide with the new Pro Series Optic’s plate. The rear sights stay in place when the optic plate is removed.

The high viz day and night sights are a nice touch.

The new slide series will fit the Leupold Delta Point, the ROMEO1PRO, ROMEO2, and even the Trijicon RMR. The extra mounting options are a nice touch, and it’s not done through a plate system like the Glock MOS. They all direct mount to the slide with ease.

Ain’t she a beaut?

The slide is equipped with SIG’s own all-metal night sights, and even without an optic, it’s a very capable choice for weapon slide. Plus, it comes in FDE, and FDE is always cool.

X-Series Compact Grip Module

Next, I needed to choose my grip module, and I’ve always thought the X-Series grip modules were what SIG should have gone with in the beginning. With a compact slide, I could’ve chosen the Carry or Compact size. I preferred the Compact size.

The X-Series Grip Modules make several changes and are well worth the humble price increase. This includes utilizing the full grip size and outfitting it with grip texture to the very top.

The X Series grip series is absolutely fantastic.

Additionally, the X-Series grip utilizes a larger beavertail at the rear and a more aggressive undercut at the trigger guard. This allows me to get my big hands higher up on my P320.

A higher grip allows for more control, and more control is better than less control. When you go smaller with a gun, you predict a loss of control associated with a smaller grip and more recoil. So any extra control I could get would be critical. Plus, I have XL-sized mitts, and I didn’t want my hands hanging off the gun. The higher trigger undercut and a high grip made it easier to maintain that control.

Legion Trigger

The Legion series trigger was made available for the SIG P320 series, and I jumped right on it. Why use something average when SIGs best trigger is available on the market for a relatively low price? The Legion series trigger offers a flat-faced, skeletonized trigger that provides an ultra-smooth and very light pull.

The reset is downright chunky and both audible and tactile when released and reset. If I want to maximize accuracy and eliminate human error (I.E., my poor trigger manipulation), then I want the very best trigger I can get. The Legion trigger series is outstanding and offers a duty-ready trigger with a lot of refinement.

The Legion flat faced skeletonized trigger is absolutely brilliant.

The pull is slightly lightened, but not to the point where it’s a poor duty trigger. Instead, it’s smoother, crisper, and generally a much better trigger. Lighter is always necessary and not synonymous with good.

I do like the very consistent break and pull. I always know what to expect and can fire quite rapidly and quite accurately. It’s a great combination with the grip and with the next item on my list.


Something with a red dot footprint clearly needs a red dot, right? I had a number of choices with the Pro series cuts but stuck with SIG. The ROMEO1PRO might mean hitting capslock every time I type it out, but it also gives me a massive window. Seriously, it’s larger than even the Deltapoint by a slight bit.

An optional metal shroud offers a high degree of protection to the optic. It’s rugged, extremely strong, and grants an entirely different level of protection to this big optic. The lens is quite clear, and the red dot is super freaking bright. The battery life quadrupled from the original ROMEO1 to 20K hours on a single battery.

Red dots are a fantastic upgrade to any gun.

The dot comes in 6 and 3 MOA, and I went with the 3 MOA. It’s a bit more precise but still large enough to be easily seen. When I combine the red dot with the Legion trigger and the X-Series grip module, I get a weapon that’s quite easy to control and shoot rapidly. The red dot makes it quick to get on target and quick to recover between shots.

If I want to back off all the way to 50 yards, I can reach out and keep gongs spinning over and over. It’s absolutely a blast to hear that loud ding at 50 yards on a 6-inch gong.

The Magazines

For daily carry, I keep it simple with a standard P320 15-round magazine that fits flush with the grip. However, for home defense and reloads, I pack the 21-round magazines designed for a little extra firepower. Who wouldn’t want a little extra ammo when it’s available. Sadly, I missed a run of the FDE 21-round mags and am stuck with the black. I know; it’s a shame not to tactically match.

I need those FDE baseplates

Popping P320 Pills

The P320 is an awesome firearm that allows a crazy amount of customization. It’s almost AR-like in the fact you can build it a piece at a time and develop the gun into what you want it to be. I’m still looking at alternative grip frames, threaded barrels, and more to keep the customization alive. Now I need a foam cut box to keep it all in.

Shop for a P320!


Travis Pike

Travis Pike

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