The SIG Sauer Hexium 556 Inconel 5.56 NATO suppressor is the heat-tolerant steel model in SIG Sauer’s additive-manufactured Hexium line (SIG Sauer part no. HEXIUM556INC). Its 3D-printed core and body are Inconel, a nickel alloy that resists heat and erosion, and the internal geometry is tuned for low back pressure. It measures 5.9 inches and mounts through a HUB-compatible direct thread steel mount cut 1/2-28, the standard AR-15 muzzle pitch. It suits AR-15 and short-barreled 5.56 builds that see heavy use.

Key Specifications

• The caliber rating is 5.56 NATO, the one cartridge this Inconel Hexium is rated for.
• The body is Inconel, a nickel alloy that stands up to sustained heat.
• Length is 5.9 inches, a compact can for a carbine or short rifle.
• Weight is 19 ounces, the figure SIG lists for the Inconel model.
• Diameter is 1.75 inches, matching the rest of the Hexium line.
• The mount is a HUB-compatible direct thread steel mount, a quick way to put it on the barrel.
• The thread pitch is 1/2-28, the standard muzzle thread on AR-15 barrels.
• The core and body are 3D-printed with additive manufacturing, giving the internal geometry its low back pressure.
• A tool-less modular end cap provides an accessory mounting system at the front.
• The exterior has an external hex pattern with black high-temperature Cerakote, for a durable finish.

Frequently Asked Questions

Will it fit my AR-15? If the barrel is threaded 1/2-28, yes. The HUB-compatible direct thread steel mount is cut to that pitch.

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.

How does the Inconel Hexium differ from the titanium models? SIG lists the Hexium line as three titanium models and one Inconel steel model, and the Inconel one is rated for 5.56 NATO. This Inconel model weighs 19 ounces at 5.9 inches.

Buy the SIG Sauer Hexium 556 Inconel 5.56 NATO Rifle Suppressor, Direct Thread

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 SIG Sauer‘s suppressors and suppressed firearms lineup and our Lubbock, Texas team will handle the transfer, and it ships fast to your Class 3 dealer.