Gunslinger ADC, Work in progress.
We got a decent amount of adcs. Some use bows, cross bows, Long range Guns, Boomerangs, machine guns/rockets, dual pistols(?) and even a double barrel shotgun?(graves)
but we don't have a Single Revolver wielding champion. So I vote for a cowboyish or outlawish theme champion
I had a Male in mind for this ADC. We have a good amount of Female adcs lately so Im not sure if the next one should be a Female. This could be a male or female champion. Many ways of going about it.
This Revolver should be a single action Revolver. Which needs to be cocked for every Auto Attack and reloaded after running out of bullets.
You should have only 6 bullets, After using 1 or all, you can/have to reload. This brings a different style of playing adc. Where reloading is part of its kit. But after reloading you gain increased damage for a short time depending on the amount of bullets you reloaded.
Auto attack animation should consist of cocking the hammer then firing the trigger and re do again for the next auto attack
The revolver Should have range greater than
but less than 
This champion could also use a Shotgun carried in on their back because why not. Which has the same range as the Revolver but It deals less damage depending on how far the target is and could hit more than 1 target.
I'm bad at math so I am not sure how to figure correct damage Ratios. Uses Mana and a Bullet resource.
Passive -(working name in progress) Hold 6 bullets in the Revolver- After 3 seconds of not Attacking a target or if empty will reload each Chamber based on auto attack speed(taking no more than a maximum of 1 seconds for reloading 2 bullets) After Using Quick Reload will gain a charge for each 6 Bullets. This charge increases Damage for each Auto attack by a % amount (Upgraded when leveling ultimate) Passive reloading could be canceled by Attacking or by getting Crowd Controlled. If Crowd Controlled during Passive reloading ends, The champion will begin back at reloading. Q - Quick Fire -When toggled Gains increased Attack speed. You are able to fire the Revolver(or Shotgun) at increased speed similar to this video https://youtu.be/cGaYqd9Pjlg?t=9s but with a more Hollywood flare imo by using 1 hand to pull the trigger with the other hand cocking the revolver hammer.
W - Pump Shotgun = Switches to Shotgun. Does more damage the closer the target is. Auto attacks can be blocked and spread out in a Cone (similar to
volley) Fires 8-10 Pellets each Shot. Does not require reloading but consumes Mana for each Shot
E - (Revolver) Quick Reload = Using this skill will reload empty bullet slots instantly depending on how many is left. https://youtu.be/WzHG-ibZaKM?t=51s be on a low cool down but consume a good deal of mana. E - (Shotgun Melee) 2 Piece = Single Target melee with 200 attack range that Stuns the enemy for 1 second. If a target is stunned by 2 Piece the next auto attack to that target takes increased damage based on the hit pellets.
R - 1 Shot Revolver = Pulls out and Fires a Huge Revolver (projectile skillshot) that Blows the user backwards for a short distance (capable of jumping over small walls). The skill Shot has a range for about 1400. Deals extra AP damage to its flat ad damage, based on the targets missing health. Considering in this skill working with the E reload skill but could only reload it at rank 2 for a total of 2 shots and rank 3 for a total of 3 shots. If so The the ultimate would need to be a toggle with perhaps Q Proc'ing each shot and the E be able to reload it at rank 2 once and being able to reload it 2 individual times at rank 3
As for the Ultimate. Gunslingers either used 2 Revolvers, Shotgun or a rifle. Shotgun was for close quarters but was quickly thrown to the side when empty, 2nd revolver was to avoid having the need to reload as often when 1 gun ran out. The Rifle was a long range accurate weapon. Gunslingers/cowboys couldn't carry everything and to avoid the Champion having a ultimate where they fire 2 Pistol/Revolver like weapons like lucian or Miss fortune in a spam...I decided to go with 1 Shot Revolver. Its a strong Revolver that Fire only 1 Shot.
There is a lot to be improved on. Its quite possible this would be too difficult in League of Legends for an ADC. It would require the adc to Conserve Bullets and Mana or risk running out of bullets and could possibly leave the adc almost Weaponless if stopped by CC(canceling passive reloading) or re continues their auto attack without stopping to reload when trying to hit minions.