Otter Creek Labs Polonium K - Silencer 5.56 1/2X28 Black

The Otter Creek Labs Polonium K is a compact 5.56 suppressor engineered for serious shooters who demand real-world performance without marketing hype. Built from H900 heat-treated 17-4 stainless steel using a CNC welded tubeless design, this silencer is purpose-built to handle hard use while keeping weight and size practical. The K variant measures just 4.8 inches and weighs 11.5 ounces, making it one of the best balanced options for hunters, tactical shooters, and range enthusiasts who want hearing protection without a bulky can on the muzzle.

The Polonium K's 6mm bore handles 5.56 NATO and any compatible 6mm/.243 cartridges. What sets it apart is the engineering: exterior material is strategically removed to cut weight while maintaining structural strength, resulting in roughly 10% more surface area than comparable designs. That extra cooling surface sheds heat faster and helps the suppressor stay manageable during extended shooting sessions. The integrated flash hider—both internal and external—delivers measurable flash reduction, particularly valuable for night vision use or low-light hunting where muzzle signature matters.

Mounting is straightforward: the Polonium K features industry-standard 1.375×24 rear threads, so you can choose your preferred mounting system rather than being locked into one proprietary solution. The package includes the suppressor, a 1/2×28 direct thread adapter, a tube clamp for easy mount changes, instruction materials, and stickers. This is a suppressor that doesn't rely on inflated decibel claims or vague marketing—the Polonium series has built its reputation on consistent, field-tested performance at a price that makes sense.

Key Features

• Compact 4.8-inch K-length design for modern short-barreled rifles and handy hunting platforms
• Lightweight at 11.5 ounces—minimal impact on handling and balance
• H900 heat-treated 17-4 stainless steel; CNC welded tubeless construction rated for hard use
• Enhanced cooling geometry with 10% additional surface area for faster heat dissipation
• Integrated internal and external flash hider reduces muzzle flash in low-light and night vision applications
• 6mm bore compatible with 5.56 NATO and .243/6mm cartridges
• Universal 1.375×24 rear mounting threads—use the mounting system of your choice
• Includes 1/2×28 direct thread adapter and tube clamp for versatile installation options

Specifications

Frequently Asked Questions

What's the difference between the Polonium and Polonium K?

The Polonium K is the compact variant of the Polonium series. The K model is 4.8 inches long and weighs 11.5 ounces, making it ideal for short-barreled rifles, hunting rifles, and shooters who prioritize maneuverability. Both use the same core H900 17-4 stainless construction and deliver the same sound and flash performance—the K simply does it in a smaller package.

Will the Polonium K work with my AR-15 or 5.56 rifle?

Yes. The Polonium K has a 6mm bore and accepts 5.56 NATO ammunition. It comes with a 1/2×28 direct thread adapter for standard AR-15 muzzles. The universal 1.375×24 rear mounting threads also allow you to use any compatible mounting system (piston, brake, etc.) if you prefer that setup.

Is the Polonium K rated for .243 or other 6mm rounds?

The 6mm bore is compatible with .243, 6mm, and other compatible 6mm cartridges in addition to 5.56 NATO. This cross-caliber compatibility makes it a versatile choice if you shoot multiple rifle platforms.

What's in the box?

The Polonium K comes with the suppressor itself, a 1/2×28 direct thread adapter, a tube clamp for installing or changing mounts, an instruction pamphlet, and stickers.