The Otter Creek Labs Polonium-K is a duty-rated, hard-use 5.56 suppressor built for people who want the best size, weight and price for its sound performance and then intend to beat on it. It is CNC welded from H900 heat-treated 17-4 stainless in a tubeless design, 4.8 inches long and 11.5 oz without a mount. The bore is 6mm, so it also covers 6 ARC, 6 Creedmoor and 243. This is the Black Cerakote version.
A flash hider is built into the end cap and the internals, so it cuts flash on night vision and in low light noticeably better than most of the competition. The machined exterior cuts weight and adds about 10% more surface area to shed heat. It ships with a 1/2x28 direct-thread adapter and has the universal 1.375x24 rear thread for any HUB mount. Made in London, Kentucky, with a lifetime warranty.
Why it stands out
- 4.8" and 11.5 oz, H900 17-4 stainless, tubeless
- Built-in internal and external flash hider
- Full-auto rated; belt-fed rated on 16" 5.56 guns (300-round strings)
- 6mm bore: 5.56, 6 ARC, 6 Creedmoor, 243
- 1/2x28 direct-thread adapter included, 1.375x24 HUB rear thread
- Lifetime warranty
Specifications
| Caliber | 5.56 NATO / 223 Rem and 6mm |
|---|---|
| Length | 4.8" (no mount) |
| Diameter | 1.625" |
| Weight | 11.5 oz (no mount) |
| Material | H900 heat-treated 17-4 stainless steel |
| Mount | 1/2x28 direct thread (included); 1.375x24 HUB rear thread |
| Finish | Black Cerakote |
| Full-auto rating | Yes |
| Part number | POLK |
| UPC | 664533654156 |
In the box
- Suppressor
- 1/2x28 direct-thread adapter
- Tube clamp
- Instruction pamphlet, stickers
Barrel length minimums
7.5" for 5.56 and 7.62x39; 10.5" for 6 ARC and 6.5 Grendel; 12.5" for 243, 6mm Creedmoor and similar. This is a 5.56/6mm can: do not shoot 6.5 or 30-cal bullets through it; for a one-can-does-all rifle suppressor see the Polonium-30.
Buying a suppressor from Guns 2 Ammo
Suppressors are NFA items and are serial-number tracked. Order online or in store, then complete your transfer at our Mesa shop, either as a registered eForm 4 or same day on a Form 4473. Buy it from us and there is no transfer fee. We explain both options, fees and timelines on our NFA & Class III page.
Outside Arizona? We can ship to your local SOT dealer to complete the transfer. Not available in CA, DC, DE, HI, IL, MA, NJ, NY or RI.
Questions? Call (602) 715-2677.
| Manufacturer | Otter Creek Labs |
| Model | Polonium-K |
| Caliber | 5.56 NATO / 223 Rem |
| Type | Silencer |
| Finish | Black Cerakote |
| Material | Stainless Steel |
| Size/Length | 4.8" |
| Item Weight | 11.5 oz |
| Diameter | 1.625" |
| Mount Type | 1/2x28 Direct Thread / 1.375x24 Universal |