The Radical Defense LS5 5.56mm is a rifle suppressor that mounts through Radical Defense’s KFM system at a 1/2×28 thread, the standard AR-15 muzzle thread. Instead of threading directly onto the barrel, the suppressor locks onto a KFM flash hider, which makes it quick to take on and off. Radical Defense builds the LS5 as the 5.56 rifle model in its LS line. That makes it a fit for rifle-length AR-15s as well as shorter carbines with a threaded muzzle. It is a straightforward choice for a 5.56 shooter who wants a can that mounts to a flash hider.

Key Specifications

• Caliber rating is 5.56mm, the cartridge most AR-15 rifles are chambered for.
• It is a rifle suppressor, the 5.56 model in the LS line.
• The mount system is KFM, which locks the suppressor onto a KFM flash hider.
• The thread pattern is 1/2×28, the standard 5.56 AR-15 muzzle thread.
• The suppressor does not thread straight onto the barrel, so mounting it does not wear the barrel threads.
• With the can removed, the flash hider stays on the rifle, so the muzzle keeps its flash control.

Frequently Asked Questions

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 LS5 mount? Through the KFM system. A KFM flash hider threads onto a 1/2×28 muzzle, and the suppressor locks onto it.

Is there a titanium LS5? Yes. Radical Defense makes the LS5TI as the titanium version. This is the standard LS5.

Buy the Radical Defense LS5 5.56mm KFM Rifle 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. Pair it with a KFM flash hider on a 1/2×28 barrel and it is ready for the range. Order through Radical Defense‘s silencers and suppressed firearms lineup and our Lubbock, Texas team will handle the transfer.