The Dead Air Sierra 5 KeyMo 5.56mm is a full-auto rated suppressor from Dead Air (Dead Air part no. SIERRA5KM), built for professional use and heavy firing schedules. Dead Air refuses to cut costs with stainless baffles in this model, using welded Cobalt 6 baffles inside a stainless steel tube instead. It balances overall sound and flash suppression while keeping a compact footprint of 4.87 inches before the mount. This version uses Dead Air’s KeyMo quick-detach system on the HUB-compatible 1.375-24 thread. Dead Air lists no barrel restrictions, so it suits a short duty or training AR.

Key Specifications

• Dead Air lists it as full-auto rated, the rating behind its heavy-use reputation.
• Barrel restrictions are none, so short-barreled hosts are within Dead Air’s limits.
• The caliber rating is 5.56 NATO and .224 Valkyrie, as stated by Dead Air.
• Energy is rated to 2200 ft-lbs, the ceiling for this design.
• Bore diameter is 5.56mm, matching the rated calibers.
• Length without a mount adapter is 4.87 inches, which keeps the rifle short.
• Weight without a mount adapter is 10.8 ounces, which keeps the front end light.
• Diameter is 1.5 inches, a size that fits most rifle handguards.
• The core is welded Cobalt 6 baffles in a stainless steel tube, built to take heat without losing lifespan.
• The mount is KeyMo on a 1.375-24 HUB thread, so other HUB adapters can be swapped in later.

Frequently Asked Questions

What calibers is it rated for? Dead Air’s published caliber rating is 5.56 NATO and .224 Valkyrie, with a 2200 ft-lb energy rating.

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.

What finish does it have? Dead Air finishes the Sierra 5 in black Cerakote over the stainless tube.

Buy the Dead Air Sierra 5 KeyMo 5.56mm Full-Auto Rated 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 Dead Air‘s silencers and suppressed firearms lineup and our Lubbock, Texas team will handle the transfer. A duty-grade 5.56 can with no barrel restriction is the simple choice for a short carbine that will see a lot of rounds.