PEW Science published its Blackbird F556 test on September 16, measuring the titanium suppressor on the laboratory’s standard untuned 10.3-inch MK18 with Federal XM193 55-grain ammunition. The tested direct-thread configuration earned a 43.7 composite Suppression Rating, with a 43.4 muzzle rating and 29.6 at-ear rating. PEW Science placed that result in the top five of its public MK18 rankings as of publication. Those numbers apply to this host, ammunition, mount, and free-field test protocol, not every rifle or environment.

Tested configuration

The F556 is a .243-caliber, or 6mm, centerfire rifle suppressor optimized for 5.56x45mm NATO and also described as compatible with cartridges such as 6mm ARC. Its body is 1.63 inches in diameter and 5.4 inches long without a mount. The included direct-thread mount increased tested length to 5.78 inches. PEW Science measured the titanium core at 8.1 ounces and the mount at 2.5 ounces, producing a 10.6-ounce tested system. The rear uses 1.375-24 HUB threads, leaving room for compatible mounting systems other than the tested direct-thread unit.

Blackbird offers titanium and Haynes 282 versions. PEW Science tested titanium, then separately reviewed manufacturer blast data from a quick-detach Haynes model. The laboratory said the results were likely representative of both versions on this weapon system, with a reasonable degree of confidence, but noted differences in consistency. It hypothesized that the tested titanium model’s lower thermal mass contributed to heat-soak behavior. Mounting differences and other unknowns prevented a definitive conclusion, so the Haynes configuration should not be treated as if PEW Science directly ran it through the same program.