The SOF 556 is a compact 5.56mm rifle suppressor built for semi-automatic and select-fire platforms. It is 3D printed in Inconel 718 using metallurgical additive manufacturing and measures 5.30 inches long with a 1.63-inch diameter. At 15.4 ounces, it carries a NANO G coating meant for high-temperature use. SOF lists it with an unrestricted minimum barrel length, so it fits a wide range of 5.56 rifle configurations. It is a hard-use option for a suppressed AR-15.

Key Specifications

• The caliber is 5.56mm, the standard cartridge for AR-15 and M4-pattern rifles.
• Overall length is 5.30 inches, a compact size for a rifle can.
• The material is Inconel 718, 3D printed with metallurgical additive manufacturing for heat resistance.
• The mount is a HUB 1.375×24 interface, compatible with HUB-pattern mounting systems.
• It is full-auto rated with an unrestricted minimum barrel length and a listed maximum velocity of 3,300 FPS.

Frequently Asked Questions

What mount does the SOF 556 use? It uses a HUB 1.375×24 mounting interface, which works with HUB-pattern mounting systems.

Do I need ATF approval to buy this? No. As of October 9, 2026, ATF no longer requires Form 4 approval, registration or a tax stamp for suppressors. It transfers on a Form 4473 with a background check through a Class 3 (SOT) dealer. State and local laws still apply.

Buy the SOF 556 Suppressor, 5.56mm, HUB 1.375×24

As of October 9, 2026, this suppressor transfers on a Form 4473 with a background check at your Class 3 (SOT) dealer, with no Form 4 or tax stamp; state and local laws still apply. Order through SOF’s suppressors lineup and our Lubbock, Texas team will handle the transfer and it ships fast to your Class 3 dealer. For a suppressed 5.56 rifle that sees hard use, the SOF 556 pairs a printed Inconel body with a standard HUB mount.