Yankee Hill Machine’s YHM Fat Cat 5.56mm QD suppressor packs full-size performance into a compact can and comes with the sRx Q.D. adapter and Mini muzzle brake it needs to mount (brand part no. YHM-2200-MB-28). The adapter and the 1/2×28 Mini Q.D. brake ship together with two suppressor wrenches. Its 1.94-inch diameter adds internal volume for a lower tone, while the baffle geometry is designed to reduce blowback toward the shooter. Construction pairs heat-treated 17-4 stainless steel with a Cobalt 6 blast baffle, and the can is full-auto rated for rigorous use. It is a strong fit for a short 5.56 carbine where every inch of overall length counts.

Key Specifications

• It is rated for 5.56mm, the cartridge the Fat Cat was built around.
• Minimum barrel length is 10 inches for 5.56 NATO, according to Yankee Hill Machine.
• The included sRx Q.D. adapter lets the suppressor attach to and detach from the muzzle brake quickly.
• The included muzzle brake is the sRx 1/2×28 Mini Q.D., sized for the standard 5.56 muzzle thread.
• The suppressor measures 4.25 inches, growing to 4.50 inches once the adapter is installed.
• It weighs 11.2 ounces, or 13.2 ounces with the adapter.
• Its 1.94-inch diameter gives the gas more room to expand.
• Materials are heat-treated 17-4 stainless steel with a Cobalt 6 blast baffle, a pairing built to survive heavy fire.
• The body threads to the 1.375×24 HUB standard for use with HUB-compatible mounts.
• It carries a full-auto rating and a published 139 dB sound rating.

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.

What comes with this Fat Cat? Yankee Hill Machine supplies the Fat Cat with an sRx Q.D. adapter, an sRx 1/2×28 Mini Q.D. muzzle brake and two suppressor wrenches.

How short is it on a rifle? The suppressor is 4.25 inches long, or 4.50 inches with the sRx adapter installed, which Yankee Hill Machine says is a full inch shorter than its Turbo K with the adapter.

Buy the YHM Fat Cat 5.56mm Suppressor with sRx Q.D. Adapter and Mini Muzzle Brake

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 Yankee Hill Machine‘s silencers and suppressed firearms lineup and our Lubbock, Texas team will handle the transfer, and it ships fast to your Class 3 dealer.