The modular design of the Sig P320 revolutionized how we view handguns. The trigger components are serialized, unlike other pistols. This revolutionary concept allows the stock to be easily replaced if it becomes damaged or worn out. It opened up a world of possibilities for civilians. The Sig Sauer Fire Control Unit (FCU), now available in the P365, offers even more options.
The Sig Sauer P365 is a FCU.
For about $40 you can replace your entire grip. Sig has applied the same construction method to their popular P365 micro-compact concealed carrying pistols.
Fire Control Units is the term used to describe the bundle that the ATF considers a firearm. These handy units are only part of a Sig P365 that you can get from a gun store. It is also the only part that requires a 4473.
You can order the rest of a “gun” including the barrel, slide and recoil assembly from Sig, or any of many aftermarket companies, and have it shipped directly to you.
Build It Your Own Way
The FCU gives you the freedom to start over if you wish. You don’t have to buy the entire pistol and then replace each part until you get the gun you want. With it, you’ll have a collection of parts that could almost make an entire gun. Starting with a serialized FCU allows you to choose from Sig or aftermarket parts.
To demonstrate this, we began with a Sig Custom Works FN FCU and built a complete pistol out of Sig parts. I chose a 365XL build because I like muzzle energy, and also to have my entire hand on the gun. It’s not difficult to convert it to a standard version of the 365 with the FCU.
The FCU can be installed by those with strong hands without the need for a tool. Anyone else can use a blunt item to drive in the pin that connects the FCU and the grip module. As expected, it handled and ran like any other Sig P365 XL. It had a nice “my way’ feel to it.
After establishing a baseline, we began to explore aftermarket options. We wanted to see how they affected the feel and performance. Our goal was to elevate an already excellent pistol to the next level. We hoped to tame the snappiness of small pistols.
Barrel Selection
You’ll probably never shoot out a factory barrel. But what if you want to upgrade or start from scratch? What other options exist? We tested samples from Zev Technologies, True Precision and other companies.
The Zev Technologies Z365XL Pro has a DLC finish, dimpling and a slightly modified hood profile. There is no information about the type or method of rifling. The DLC coating has a lot of appeal, both in terms of practicality and aesthetics. Diamond-like carbon coatings are so named because they impart diamond characteristics to the surface.
We enjoy the characteristics of firearm parts such as corrosion and abrasion resistant, and a slickness which acts almost like a dry grease. This means that dirt can be easily removed from a pistol barrel. Not to mention a smoother operation, as the slide glides along the barrel hood when cycling.
The dimples are aesthetically pleasing and increase the surface area of the barrel for better cooling. The Sig P365 XL barrel’s weight is also reduced from 2.6 ounces at the factory to 2.5 ounces. It’s not a huge weight saving, but it is there.
The Zev barrel was very accurate and smoothed out the pistol’s cycling a bit. It’s impossible to measure without a lab, but the racking and recoil did feel smoother. After a few dozen cycles, the coating on our barrel showed signs of wear.
True Precision Options on the P365 XL
True Precision offers a wide range of options for the Sig P365 XL. There are threaded and regular lengths as well as seven different coating options. We chose the threaded version, not because we wanted to use the threads but rather to increase the barrel length of the 365XL from 3.7 to 4.5 inches.
The flutes added only three tenths of an inch to the weight. The fluting did, however, improve ballistic performance and meet or exceed the performance of many duty-sized firearms. True Precision’s barrels use certified 416R match grade stainless steel. The six-grooved rifling has been broach cut with a proprietary technique to be compatible for all bullet types including cast lead.
The feed ramp has also been improved and leads to the fully supported chamber. Our sample was titanium nitride-coated, giving it a golden color and increased corrosion and wear resistance. The aesthetics also matched the Sig Customworks FCU.
Super Slides
The aftermarket is still catching up with 365 XL. A few shops offer to work on your existing slide. There aren’t many complete slides. On the Sig Custom Work website, you can choose from eight different options. Our choice was the Spectre Slide.
The Spectre is a new aesthetic, but it’s also a more practical option. It reduces the reciprocating weight from 10.1 ounces for a standard slide with no optic to 9.3 ounces when a Romeo Zero is mounted! A gun that cycles faster and feels less recoil is made possible by a smaller reciprocating mass.
Recoil Assembly
The standard spring is available from Sig, but my experience with DPM Systems’ products led me to purchase their 365XL kit. These tunable recoil system are made up of three springs. These springs work together to gradually decelerate the slide following firing, and then progressively accelerate it back into battery.
In some firearms they also prevent the largest source of felt recoil, when the slide’s travel bottoms against the frame. Since discovering the Greek company at SHOT Show years ago, I’ve enjoyed using their solutions in ARs and AKs as well as several pistol models. The DPM System has not made a huge difference with every pistol, but it has been a game changer for others.
We are pleased to announce that the DPM System is a significant improvement for the 365 XL. The kit comes with three springs that can be changed by the user to adjust the action to the ammunition you will be using. It is crucial to do this with a carry-gun. Check that your defensive ammunition will work with the gun! The longest spring we used worked well for our build and reduced the recoil force.
Frame Jobs
With Sig’s FCU, the frame, or grip modules, versatility is a real delight. The frame can be modified without destroying the entire “firearm” as is the case with most other pistols.
Sig Custom Works offers three color options and one laser-stippled black option for the 365 XL at the time this article was written. There are some interesting aftermarket options available thanks to Sig’s encouragement. Icarus Precision has done some amazing work in aluminum.
The Icarus Precision A.C.E. The Icarus Precision A.C.E. This increases the weight of the pistol, allowing it to be balanced lower in the hand.
The X Elite grip module is more than just lighter. It offers better grip all around and a stronger hold. The aggressive double undercut on the triggerguard allows for a higher hold. The first undercut gives the middle finger of the firing hand more room. The second undercut allows the support hand to grip the gun higher.
The X Elite, PRO Elite and PRO Elite models have a “gas-pedal” extension on the left side of the frame. This allows the thumb support to rest, and provides a downward force that counters muzzle rise when firing.
Two rail slots are included on the dust cover of the 365 FCU, allowing the pistol to be fitted with a wide range of light and laser accessories.
Holstering the X Elite Grip
The X Elite grip module places the pistol further in the hand due to its weight and undercuts. If you choose the gas pedal, the holster will not fit. The Warcat Tactical holster was the home of the 365 XL before the frame swap. It will not fit the A.C.E. X Elite grip module.
I then tried a Crossbreed Holster, hoping that the leather would stretch to fit. Crossbreed’s holsters are too good for that. There are holsters that are specifically designed for this grip module. You can find the perfect holster for you with a quick search.
The Upshot
Our build demonstrates the advantages that the Sig P365 offers. We were able “build” our pistol to our liking for a lower total cost than buying a pistol and then purchasing aftermarket components.
We chose two full metal jacket range and three defensive loads to test the range. The five loads were fired through each barrel.
The muzzle energy for each load fired was calculated. This is why you feel a little extra punch with certain loads. The testing was done at 10 yards, free-standing as a demonstration of a defensive gun.
The three barrels all performed well, and provided mechanical accuracy that most shooters cannot match. The average group size was only 0.27 inches different between the three barrels and the five loads. Each barrel had its own favorite load, just like rifle barrels.
How will you build it now that we have seen how different FCUs can be?
Visit SigSauer.com for more information. Also visit ZEVTechnologies.com True-Precision.com IcarusPrecision.com and DPMSystems.com.
The Performance of a
1. Sig P365 FCU with Zev BarrelLoadVELOCITYENERGYACCURACYPMC Bronze 115 FMJ1,0542840.69ZQI 124 FMJ 1,0703150.68Hornady Critical Defense 1151,0762961.02Hornady Critical Duty 135 +p1,0923570.96Sig Elite Performance 124 JHP1,1713771.03
2. Sig P365 FCU with True Precision BarrelLoadVELOCITYENERGYACCURACYPMC Bronze 115 FMJ1,0532831.19ZQI 124 FMJ 1,078 3200.96Hornady Critical Defense 1151,0903031.29Hornady Critical Duty 135 +p1,0793490.76Sig Elite Performance 124 JHP1,1793831.54
3. Sig P365 FCU with Sig Factory BarrelLoadVELOCITYENERGYACCURACYPMC Bronze 115 FMJ1,0292701.0ZQI 124 FMJ 1,079 3210.86Hornady Critical Defense 1151,0722930.37Hornady Critical Duty 135 +p1,102 3641.35Sig Elite Performance 124 JHP1,1903901.6
Bullet weight in grains, velocity by chronograph in feet per second, energy in foot pounds (fpe), and accuracy in inches are the best five-shot groups for 10 yards.
This article was originally published by Combat Handguns in their May/June issue of 2022. Subscription is available in print and digital editions at OutdoorGroupStore.com. Or call 1-800-284-5668, or email [email protected].
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The post FCU Spells freedom: Testing the Sig Sauer P365 fire control unit appeared first on Personal Defense World.
