The Daniel Defense SG-556 suppressor is the dedicated .223 and 5.56mm can in the SoundGuard line, powered by KGM technology (Daniel Defense part no. 06-140-04249). It is built from a lightweight but durable stainless steel tube and baffle stack, so it holds up to carbine-pace shooting. Gas-flow dynamics eliminate over-gassing and push most of the gas forward, which keeps blowback out of the shooter’s face on a direct impingement AR. The suppressor attaches by direct thread through an included 1/2×28 adapter built on the HUB standard, and it threads on or off in seconds. For an AR-15 owner who wants a purpose-built 5.56 can rather than a .30 caliber compromise, it is a clean fit.

Key Specifications

• Caliber rating is 5.56mm and .223 Rem, so the can is built specifically for AR-15 cartridges.
• Length is 7 inches, a practical size on a carbine or a short-barreled rifle.
• Diameter is 1.75 inches, so confirm clearance under your handguard and optic.
• The tube and baffle stack are stainless steel, chosen for durability under sustained fire.
• The included mount is threaded 1/2×28, the standard 5.56 muzzle thread.
• Attachment uses the HUB standard 1.375-24 UNS, so KeyMo, ASR and other HUB mounts also fit.
• Gas-flow dynamics eliminate over-gassing and send most gas forward instead of back at the shooter.
• A patent-pending baffle stack and proprietary internal coating reduce flash signature to virtually zero.
• Patent-pending gas-flow pathing gives minimal point-of-impact shift when the can goes on or comes off.
• It is made in the USA and carries Daniel Defense’s 100 percent satisfaction guarantee.

Frequently Asked Questions

What calibers is the SG-556 rated for? Daniel Defense lists it for .223 Rem and 5.56mm firearms. For .30 caliber rifles, the SG-30 family is the SoundGuard choice.

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.

Can I use a quick-detach mount instead of the direct thread? Yes. The SG-556 uses the HUB standard 1.375-24 UNS, so in addition to the included 1/2×28 direct-thread adapter it accepts other HUB mounts such as KeyMo and ASR.

Buy the Daniel Defense SoundGuard SG-556 Suppressor, 5.56mm, 1/2×28

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 Daniel Defense‘s suppressor lineup and our Lubbock, Texas team will handle the transfer.