Due to its design, it doesn't get carbon fouling which is a problem with the M-16 family of weapons.
HK416: The Gun that Took Out Bin Laden
The rifle is still controversial in some circles - but is now generally regarded as superior to the M4 carbine that it replaced for this mission.
Heckler & Koch’s HK416 flew under the radar for quite some time. That all changed in May 2011, when the now-famous SEAL Team Six raided a compound in Abbottabad, Pakistan where Osama bin Laden and several of his family members had been living for nearly a decade.
During the raid and subsequent firefight, bin Laden and several of his family members were shot and killed. Although accounts of what happened differ slightly and are likely attributable to "the fog of war” and impeded situational awareness, one thing is certain: the rifle that killed bin Laden was none other than Heckler & Koch’s HK416.
Heckler & Koch HK416
The H&K416 was designed in the late 1990s as a more robust, long-lived alternative to the ubiquitous M4 carbine. Unlike the M16 and M4 family of rifles, the H&K416 uses a short-stroke piston system, rather than a direct impingement system. The advantage to the H&K416 piston design is that combustion gases generated by firing the weapon are unable to enter the rifle’s interior, reducing the amount of fouling, and consequent stoppages.
The H&K416 is designed to be similar to the M4 and M16 family of rifles to help soldiers transition from those platforms. A nearly identical layout helps facilitate weapon crossover.
Thanks in part to the H&K416’s piston design, the rifle is prized for being highly reliable with a good reputation. In addition, the rifle is regarded as highly accurate, and can reliably hit point targets at a range of six hundred meters, or area targets as far out as eight hundred meters.
Widespread Adoption