Sig P320 Full Size Barrel

SIG P320 Threaded Barrel

A SIG Sauer P320 threaded barrel is a drop-in replacement barrel with external muzzle threads for mounting suppressors, compensators, and other muzzle devices. SIG Sauer offers 3 factory threaded barrels in two thread pitches, M13.5x1 left-hand (LH) and 1/2-28 right-hand (RH), and aftermarket makers such as Ballistic Advantage and Parker Mountain Machine (PMM) add more than 71 additional options. This guide covers factory barrels, Ballistic Advantage barrels, PMM barrel and compensator combinations, installation, and suppressor setup for the SIG P320.

What Is a SIG P320 Threaded Barrel?

A SIG P320 threaded barrel replaces the standard barrel and adds threads at the muzzle for attaching a suppressor, compensator, or muzzle brake. The SIG Sauer P320 uses a modular design, so a barrel swap requires no gunsmith tools or permanent modification to the slide, receiver, or grip module.

How Does a Threaded Barrel Differ From a Standard Barrel?

A threaded barrel extends past the slide and carries external threads, while a standard barrel ends flush with the slide muzzle. The exposed threaded section measures roughly 0.5 to 0.75 inches (12.7 to 19 mm), and a thread protector covers it when no muzzle device is installed.

Why Does Thread Pitch Matter?

Thread pitch must match the thread pitch of the suppressor or muzzle device. SIG Sauer offers 2 pitches on the SIG P320: M13.5x1 LH (metric left-hand) on barrels without a Loaded Chamber Indicator (LCI), and 1/2-28 RH (US standard right-hand) on barrels with an LCI. A mismatched pitch will not thread on, and forcing it damages both parts.

SIG Sauer Factory SIG P320 Threaded Barrels

SIG Sauer sells 3 factory threaded barrels for the SIG P320, all in 9mm with a Nitron finish. Each barrel differs in length, thread pitch, and LCI configuration, so selection depends on the slide size and the muzzle device.

Which Factory Barrel Fits a Full Size SIG P320 Without an LCI?

SIG P320 Full Size 9mm 5.5 Inch No LCI Threaded Barrel (SKU 8900315)

The full size 9mm barrel measures 5.5 inches (139.7 mm), uses M13.5x1 LH threads, and ships under SKU 8900315. The barrel has a Nitron finish, includes a thread protector cap, and carries the SIG SAUER Infinite Guarantee. The barrel does not fit the SIG P320 X-FIVE slide.

Which Factory Barrel Fits a Compact SIG P320?

SIG P320 Compact/Carry 9mm 4.6 Inch No LCI Threaded Barrel (SKU BBL-MOD-C-9-TB)

The compact and carry 9mm barrel measures 4.6 inches (116.84 mm), uses M13.5x1 LH threads, and ships under SKU BBL-MOD-C-9-TB. The barrel has a Nitron finish, includes a thread protector, and also fits the SIG P250 Compact.

Which Factory Barrel Has a Loaded Chamber Indicator?

SIG P320 Full Size 9mm 5.5 Inch LCI Threaded Barrel (SKU 8900566)

The full size LCI barrel measures 5.5 inches (139.7 mm), uses 1/2-28 RH threads, and ships under SKU 8900566. The barrel has a Nitron finish and a Loaded Chamber Indicator (LCI) witness hole that shows when a round is chambered. The barrel does not fit the SIG P320 X-FIVE slide.

How Do the 3 Factory Barrels Compare?

The 3 factory barrels split into two groups: M13.5x1 LH for no-LCI models and 1/2-28 RH for LCI models. Length, SKU, and compatibility differ as follows:

• SKU 8900315: 5.5 inches (139.7 mm), M13.5x1 LH, no LCI, thread protector included
• SKU BBL-MOD-C-9-TB: 4.6 inches (116.84 mm), M13.5x1 LH, no LCI, thread protector included
• SKU 8900566: 5.5 inches (139.7 mm), 1/2-28 RH, LCI witness hole, Nitron finish

Ballistic Advantage SIG P320 Threaded Barrels

Ballistic Advantage offers more than 71 aftermarket barrels for the SIG P320 across 3 frame sizes. The line includes threaded and non-threaded barrels, fluted and non-fluted profiles, LCI and No LCI versions, and BLEM (blemished, discounted) variants. Prices range from $115.50 for a BLEM barrel to $205.00 for a threaded fluted barrel.

Which Frame Sizes Does Ballistic Advantage Cover?

Ballistic Advantage covers 3 SIG P320 frame sizes with 23 to 24 items each. The categories are:

• SIG P320 Full: 23 items
• SIG P320 X Compact/Sub Compact: 24 items
• SIG P320 Compact/XCarry Legion: 24 items

What Finishes and Profiles Does Ballistic Advantage Offer?

Ballistic Advantage offers 3 finishes: QPQ Black, PVD Copper, and PVD Light Gray. Fluted profiles come in bomber flutes or spiral flutes, which remove weight and add surface area for heat dissipation. Non-fluted profiles keep a plain cylindrical exterior.

Who Should Buy a BLEM Barrel?

A BLEM barrel suits shooters who want a lower price on a barrel with cosmetic finish flaws and identical function. BLEM barrels start at $115.50, and the flaws affect appearance only, not chamber dimensions or rifling.

Parker Mountain Machine SIG P320 Barrel and Compensator Combos

Parker Mountain Machine (PMM) sells SIG P320 barrel and compensator combinations for Subcompact, Compact, and Full Size slides. Each combination pairs a threaded barrel with a compensator that reduces muzzle rise, and the barrel length must match the slide length.

What Compensator Types Does PMM Offer?

PMM offers 3 compensator types: Duty, Ultra, and Micro. The Duty compensator is the largest and gives the most muzzle rise control, while the Micro compensator is the smallest and keeps the profile compact for concealed carry.

What Finishes Does PMM Offer?

PMM offers 4 finishes: Black Anodize, FDE Anodize, Black DLC, and FDE PVD. Anodize finishes apply to the aluminum compensator, while DLC (Diamond-Like Carbon) and PVD (Physical Vapor Deposition) coatings apply to the barrel for wear resistance.

Does a Compensator Require a Specific Holster?

Yes, a compensator extends the muzzle, so a SIG P320 with a PMM compensator needs a holster cut for that length. PMM recommends specific holsters for comp-equipped setups, and a standard holster for the same slide will not seat the firearm fully.

How to Install a SIG P320 Threaded Barrel

Installing a SIG P320 threaded barrel takes 4 steps: unload the firearm, remove the slide from the grip module, slide out the existing barrel, and insert the new barrel. The SIG P320 fire control unit stays in the grip module throughout, and no tools beyond the takedown lever are required.

What Are the Installation Steps?

1. Unload the firearm and confirm the chamber is empty
2. Remove the slide from the receiver and grip module
3. Remove the recoil spring assembly and slide out the existing barrel
4. Insert the threaded barrel, refit the recoil spring assembly, and reinstall the slide

How Many Rounds Does an Aftermarket Barrel Need to Break In?

An aftermarket SIG P320 barrel needs 50 to 100 rounds to break in. Function-test the firearm with the same ammunition planned for regular use, and confirm reliable feeding and ejection before relying on the barrel for carry or competition. Shooters who also run subcompact platforms can compare setups through SIG P238 accessories, and those who want a threaded barrel on a smaller SIG frame can review P365 threaded barrels.

Suppressor and Muzzle Device Setup

A SIG P320 threaded barrel supports suppressors and compensators once the thread pitch matches and the thread concentricity is verified. Suppressor use adds further requirements for sights and ammunition.

Why Does a Suppressor Require Suppressor Height Sights?

A suppressor blocks the factory sight picture, so the firearm needs suppressor height sights. Suppressor height sights sit taller than standard sights, typically by 0.15 to 0.25 inches (3.8 to 6.4 mm), and let the shooter see over the suppressor body.

What Does a Thread Protector Do?

A thread protector prevents carbon lock and thread damage when no muzzle device is installed. Carbon lock is carbon buildup that bonds a muzzle device to the threads, and the protector keeps carbon and debris out of the thread grooves.

Should Thread Concentricity Be Checked Before Suppressor Use?

Yes, check thread concentricity before the first suppressor use. Off-center threads can cause a baffle strike, in which the bullet contacts the suppressor, so a gunsmith or a concentricity gauge should confirm alignment first.

Which Ammunition Works With a Threaded SIG P320 Barrel?

A 9mm SIG P320 threaded barrel fires standard 9x19mm Parabellum ammunition. Shooters who own a SIG P320 in another chambering, or a different SIG model, can also browse .357 SIG ammo for compatible platforms.