The Battle Rifle from Halo 2 is now in Halo 5.
In Halo 5, Halo 2's Battle Rifle is a Mythic loadout weapon REQ you can deploy in Warzone mode.
It's also unlocked in Forge, if you fancy recreating Halo 2 maps and lacing them with a double dose of nostalgia.
Halo 2's BR55 fires 9.5mm rounds from a 36-round magazine, and carries a 2X optical scope for targeting. It fires in short, automatic bursts of three rounds, making it extremely accurate. I used to love this badboy back in the Halo 2 days. Ah, the memories.
Halo 2's Battle Rifle arrives as part of Halo 5's first update of 2016. It adds new battlegrounds for Arena and Warzone Assault, as well as new armour sets and weapon skins. There's more on Halo Waypoint.
Below is some footage of Halo 2 and its Battle Rifle. Warning: turn the sound down.