Your aerodynamic body gives you 1.5x movement speed in the air and in water, though only if you're facing the right way.

The Dodge Roll is an important part of the tool kit for anyone in the "Gungeon." the dodge roll allows the user to use the dodge action for a single incoming attack, moving the user 1 ft off the ground and 10 ft in the direction of the rollers choosing simultaneously. The Dodge Roll can be used as a reaction, but it takes a bit to pull off, so whenever the user uses it, they will have to sacrifice 15 feet of movement from their next turn. If the user has used up all of their movement or doesn't have enough, they can't Dodge Roll. When a Bullet Kin performs a Dodge Roll, they set off a small explosion at their feet to propel themselves. This explosion does no damage. The Dodge Roll is also a good tool for crossing small gaps. The dodge roll can be used to slide over a table of any length. You can not turn well dodge rolling. The Dodge Roll is not something every Bullet kin can do only those with lots of experience know this maneuver. (Level 15 needed to unlock)

Who needs bullets when you ARE a bullet? Provides immunity to contact damage, such as spiked or burning skin, as well as damage from being fired out of a contraption such as a canon or a ballista.

Bullet Kin have proficiency with all ranged weaponry and attacks. You can also switch between any weapon you have on you in the blink of an eye (it takes no time to switch between weapons).

You also get a +3 to your Dexterity score.

But you also get a -3 to your strength and intelligence score.

Made for the Gungeon also makes it, so Bullet Kin have disadvantage on melee attacks unless you are using a specially made weapon. 

Made for the Gungeon also makes it, so you can flip tables with no trouble whatsoever. (flip tables as a free action)

As a Bullet Kin, most of your body is made of brass, this gives your body a natural resilience (+3 to AC), but any armour you wear acts as temporary hit points instead of adding to your AC if you can find any that fits that is.