This is a website for showing the TTK (Time To Kill) for all operators' guns in Rainbow Six Siege. This is a great way to be able to tell how good mathematically certain guns are.
The code for this website uses React.js.
Extended Barrel effect: Damage * 1.12 (Rounded down)
DPS: Damage per second, calculated as (Damage * Fire Rate) / 60
Bullets to Kill 1 Armor: 100 / Damage (Rounded up)
Bullets to Kill 2 Armor: 110 / Damage (Rounded up)
Bullets to Kill 3 Armor: 125 / Damage (Rounded up)
TTK 1 Armor: (Bullets to Kill 1 Armor - 1) / (Fire Rate / 60)
TTK 2 Armor: (Bullets to Kill 2 Armor - 1) / (Fire Rate / 60)
TTK 3 Armor: (Bullets to Kill 3 Armor - 1) / (Fire Rate / 60)
Notes: This assumes every bullet is shot to the enemy's chest (not arms or legs, as shooting here would lower the damage) AND that the bullet is shot within 25 meters (for most guns, damage dropoff happens at any farther distance).
Also note that not every gun has access to the extended barrel.