(You can find all this shakes modules in Content→Blueprints→Camera→WeaponsShakes)
When the player shoots, a very subtle camera shake will appear to increase the overall feel and gameplay experience, it has to be barely noticeable.
Each gun has an unique and designed camera shake to improve experience and gunfeel, for that, the player needs a system that detects which gun are the player using to apply the correct camera shake for each weapon.
(It is important to time the shake correctly, so that it feels applied for each fired bullet).