Bullets

Bullets are the most common ammo for tanks in Free For All game mode besides Drones(Overseer/Overlord/Manager drones, and Necromancer squares). The bullets are simple red circles, that have various speeds, damage, and other attributes based on the different skills you may have developed. Arena Closer also doesn't have red ammo. Its bullets are yellow to match its team.

In the Team Deathmatch, Domination, and Mothership game modes, red team has red colored bullets and Blue team has blue colored bullets.

Types of Bullets
Gunner: These fire the smallest bullets, but can travel at high speed and do decent damage, but they have really low penetration.

Hunter + X Hunter: These fire one bullets a bit larger than the gunners and another one is bigger than the one before, have 2 and 3 bullets each sequence respectively.

Sprayer: These bullets have the exact same size as Hunter, both the bigger and smaller one, but bullet speed, damage and penetration are not as good because Hunter is in sniper class and Sprayer is a bullet spam tank.

Basic tank: These tanks fire small bullets, but only because the Basic Tank is usually lower level than other tanks, in most case beside the ones mentioned in this page, the size is the same when they are at the same level, the bigger bullets from Sprayer, Hunter and the medium size bullet from X Hunter are also the same sized.

Destroyer + Hybrid: These tanks fire the largest bullets of them all. They have really high penetrate and damage, not much normal tanks can survive this, at max penetration and damage stats, another tank with max health and body damage can only take two hits at most. Their speed is slow so it is hard to aim other tanks with these type of bullets.

Dominator: This turret fire the largest bullets too. But they have much more penetration and damage, even a bullet storm completely stop the bullet and weaken it to one bullet away to destroy it, it can still do massive damage to a max health and body damage.

Arena Closer: This tank also fires the largest bullets, but have very high speed and penetration, but have same amount of damage a Destroyer bullet has.