The Barrett M82A1 is the most powerful sniper rifle and gun in the game. It has a damage of 9/10 and is a 1 shot kill weapon if the enemy has no sniper amour. It is no longer an anti-armour weapon and can perhaps kill any player even if he has armour.
Although such guns are feared, it is really rare because it is only obtainable by gachapon draws. Due to the random nature of Gachapon, it is quite hard to obtain it, let alone special camo versions of the weapon. Every so often, a new version of the Barrett will come on sale. Such as the new Barrett OMEGA. It's godlike power is only matched by it's low magazine count.