Bighorn in TD2 is capable of putting out an insane amount of burst damage, thanks to its exotic talent. It, however, requires players to sit back and play from the cover instead of directly jumping into the heart of the battle.

The gun's exotic talent is called Big Game Hunter, which transforms the weapon into a semi-automatic rifle that provides it with +450% damage per shot when scoped.

To unlock the Bighorn AR, players will first need to complete the entire campaign of WONY and reach Level 40. Once done, players will need to farm missions and strongholds on the Legendary difficulty option.

I'd recommend running these missions/strongholds with a squad to breeze through them and increase the chances of getting it - via loot share. I'd also suggest taking a look at ARs Targeted Loot missions and farming them.

However, I should mention it here that the weapon only has a 5% drop chance, which isn't great, to begin with. May the RNG-sus be with everyone!