The SIG Sauer Hexium 556 Inconel is the high-temperature version of SIG’s 5.56 NATO Hexium suppressor (SIG Sauer part no. HEXIUM556INC). Inconel is a nickel alloy that stands up to heat and erosion, which makes it the choice for short barrels and fast strings of fire. The can measures 5.9 inches long and attaches with a HUB-compatible direct-thread mount cut 1/2-28, the standard AR-15 muzzle thread. Its HUB rear interface accepts other HUB-compatible mounts if you change hosts. It suits AR-15 and short-barreled 5.56 builds that see heavy use.

Key Specifications

• The caliber rating is 5.56 NATO, the cartridge this Hexium is built for.
• The body is Inconel, a nickel alloy that resists heat and erosion under sustained fire.
• Overall length is 5.9 inches, a compact can for a carbine or short rifle.
• The mount is a HUB-compatible direct thread, threading straight onto the barrel.
• The thread pitch is 1/2-28, the standard muzzle thread on AR-15 barrels.
• The rear interface follows the HUB standard, the 1.375×24 pattern that accepts other HUB-compatible mounts.

Frequently Asked Questions

Why choose the Inconel Hexium over a titanium can? Inconel trades some weight for greater resistance to heat and erosion, which matters on short barrels and in high-volume shooting.

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.

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

Buy the SIG Sauer Hexium 556 Inconel 5.56 NATO Suppressor

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. If your 5.56 runs hot and often, Inconel is the material to have at the muzzle.