The HK416 is a Modular rifle design from the firearm's company H&K located in Germany. The HK416 recently competed with the FN SCAR, MC-R, and XM8, to eventually replace the current U.S. military's MCR (main combat rifle), the M16A4. However, the HK416 lost the majority of the tests to the FN SCAR. As of now it does not look like a possible replacement for the M16A4.
The HK417 is a variant chambered in 7.62mm and is intended for the Designated Marksman role.
It is the primary weapon of the Norwegian armed forces and sees some use by American special forces. The weapon has become very common in many modern military shooters.