Gunslinger with discipline.

Level 3: Gunslinger Discipline

Your experience on the battlefield has refined your fighting techniques. You learn deeds that are fueled by special dice called Discipline.

Deeds. You learn three deeds of your choice. Many deeds enhance an attack in some way. You can use only one deed per attack.

You learn two additional deeds of your choice when you reach Fighter levels 7, 10, and 15. Each time you learn new deeds, you can also replace one deed you know with a different one.

Discipline. You have four Discipline. A Discipline is expended when you use it. You regain all expended Discipline when you finish a Short or Long Rest.

You gain an additional Discipline when you reach Fighter levels 7 (five dice total) and 15 (six dice total).

Saving Throws. If a deed requires a saving throw, the DC equals 8 plus your Dexterity modifier (your choice) and Proficiency Bonus.

Level 3: Gunsmith

At 3rd level, you gain proficiency with firearms and Tinker's Tools. 
You may use the tools to craft ammunition, repair damaged firearms, or possibly draft and create new ones.

Level 7: Quick Draw

Starting at 7th level, you gain a +2 bonus to initiative.  You can also draw and stow firearms as part of a movement.

Remembering the Face of Your Father

At 7th level your firearm shots count as magical for the purpose of overcoming resistance and immunity to nonmagical attacks and damage.  

Level 10: Dealing in Lead

Upon reaching 10th level, you gain expertise in the Intimidate skill, even if you did not already have Intimidate.  This allows you to use double your proficiency bonus on Intimidate checks.

Level 15: Unwavering Discipline

Starting at 15th level, when you roll initiative and have no Discipline points remaining, you gain 4 points.

Unwavering Discipline

Starting at 15th level, when you roll initiative and have no Discipline points remaining, you gain 4 points.

Level 3: Deed Options

The deeds are presented here in alphabetical order.

As a Unit

When you take the Attack action on your turn, you can forgo one of your attacks to direct one of your companions to strike. When you do so, choose a friendly creature who can see or hear you. That creature can immediately use its reaction to make one weapon attack, adding your Wisdom modifier to the attack's damage.

Cheat Death

When reduced to 0 hit points, you instead drop to 1 hit point.

Dead Eye

You can add your Wis modifier to the attack roll of a firearm shot.

Disarming Shot

If the shot hits, the target takes normal damage and must make a Strength saving throw. On a fail, the target must drop 1 held item of your choice.

Fan the Hammer

Immediately after you take the attack action on your turn, you can fire off two more shots in quick succession as a bonus action.

Fleet of Foot

Your lightning fast reflexes allow you to move quicker than anyone on the battlefield. Right before combat you can double your DEX bonus that is added to your Initiative roll; additionally, on your first turn, you can take the dash action as a bonus action.

Gone with Wind

When you are subjected to an effect that allows you to make a Dexterity saving throw to take only half damage, you instead take no damage if you succeed on the saving throw, and only half damage if you fail.

 

Gunslinger's Dodge

When a ranged attack roll is made against you, you can take a reaction to move 5 ft. with +2 AC, or drop prone for +4 AC.

Lightning Reload

You can reload any firearm as a free action. 

Parting Shot

When you take the disengage action, you can fire at a target as a bonus action. 

Pistol Whip

You can make a melee attack roll with the butt/handle of your gun against an enemy within 5 ft. of you as a bonus action after making using the attack action with your gun. This attack roll uses your full proficiency bonus and deals 1d4 + your Str modifier bludgeoning damage.

Return Fire

When a creature hits you with a ranged weapon attack, you may use your reaction to make 1 firearm attack against the creature. If you hit, add your Wisdom modifier to the attacks damage roll.

Slinger's Luck

You can reroll a saving throw or ability check and must use the new roll, even if it is lower.

Warning Shot

You can fire a shot next to a target and the target must make a Wisdom saving throw or be stunned until the start of your next turn. This consumes your action.

Whites of their Eyes

You can hold your attack action until a creature enters your firearms first range increment. You make your attack action and if at least one shot hits, you reduce their speed to 0ft until the end of your next turn.

Level 18: Widowmaker's Shot

At 18th level, you have the ability to call a truly deadly shot.  You can spend 5 points of discipline to focus on a shot so debilitating that the target must make a Constitution saving throw.  If it fails, the target is reduced to 0 hit points.  If it succeeds, it takes 10d10 necrotic damage.  You can only affect one creature in this manner once per round, and only twice per short rest