Sig Sauer NG556QD SLX 5.56NATO Black Inconel

Description

The Sig Sauer NG556 is a sound suppressor, rated for .223 REM/5.56 NATO, 7.4'' long, built in Inconel.

This is an NFA item, so the process differs from an ordinary firearm purchase. It transfers on an ATF Form 4, which requires fingerprints, a photograph, notification to your chief law enforcement officer, and an ATF background check. Since 1 January 2026 the transfer tax on suppressors and short-barreled firearms is $0, though the registration and approval requirements are unchanged. You cannot take possession until ATF approves the transfer – the item stays with us until then. It can be registered to you as an individual or to a trust.

It is rated for .223 REM/5.56 NATO. A suppressor may be used on a cartridge at or below its rating and bore diameter, but never above it – firing a larger bullet than the bore allows is how a baffle strike happens, and that destroys the suppressor.

Inconel is a nickel-chromium superalloy used where the blast baffle takes the most heat and erosion. It is heavier than titanium and is what allows a tube to be rated for sustained fire.

Suppressors reduce the sound of a shot; they do not silence it. How much quieter any given setup is depends on the host firearm, the barrel length and the ammunition – subsonic ammunition is much quieter than supersonic through the same can, because the crack of a bullet passing the sound barrier happens downrange and cannot be suppressed at the muzzle.