The Heckler & Koch HK416, more commonly known as the M416 is an improved variation of the Colt M4 and M16 assault rifles.
The 416 features a longer part lifespan, a more reliable gas-stroke piston system, and the ability to interchange many standard M4/M16 parts into the weapon such as magazines, optics, and stocks.
The 416 is in service with multiple countries as well as several factions.
A M416 with a rotary diopter sight, flashlight, vertical grip, and laser module
Ditto, with an EOTech 556 Sight
soldier pulling the charging handle on a 416