The XO16A2 Chaingun (Presumably the full name being the XOTBR-16A2 Chaingun) is a Titan weapon appearing in Titanfall 2's singleplayer campaign, wielded by Vanguard-class Titans such as BT-7274, as well as the game's multiplayer, wielded by Monarch-Class Titan that was implemented through DLC. It is manufactured by Brockhaurd Manufacturing, and is the presumed successor to the XOTBR-16 Chaingun.
The XO16A2 performs very similarly to its predecessor in the first game. It is available on the Expedition loadout in the campaign for Titanfall 2, and on the Monarch in multiplayer.
The XO16A2 is the weapon used in the Burst Core - when activated, the weapon will reload and automatically mag-dump every single round it can fire on full-automatic. When this occurs, an arc-like effect is seen on the weapon similar to the Amped XO-16, indicating the research that was conducted into electric rounds may have been incorporated into this new design. These Arc Rounds do not require the Burst Core to be active, however, and can be installed as a standard modification for the Monarch.
Other modifications for the XO16A2 include an Accelerator, allowing the Rate of Fire to ramp up over time, a Sniper Configuration that installs more advanced optics and tightens the weapon's spread and a Critical Hit modifier that increases damage dealt to enemy Titans.
The XO16A2 has the internal nickname "Shorty". This is due to the fact that the weapon has had its barrel shortened since the first game for CQC. It has also been re-coloured to match the paint scheme of BT-7274.