AutoSizeCrosshair

Automatically calculates the crosshair size based on weapon hipfire spread.
By default adjusted for 90 Vertical FOV. Adjustable in settings.

Why no shotguns? Because they're all kinds of broken. They don't even shoot where the crosshair is aiming, they shoot where the gun is physically pointing.
Their spread is double - they have a cone size which rotates all pellets around a circle, and then they have random spread on top of that, which makes for some really bs rng shenanigans.
Even if you tried to get an accurate size, it'd either be way too big for 90% of the shots, or too small and some shots would end up outside the crosshair anyway.