From left to right;

Yellow - High Explosive
Orange - Incendiary
Blue - Armour-piercing
White - Ball

Played SimplePlanes Multiplayer, expecting epic dogfights between friends, only to find out gunfire isn't synchronized between PCs? Disappointed? Well don't be! This here mod includes several weapons which use game physics to launch projectiles; meaning it should work just fine.

There are even multiple types! Ball is the standard type with decent accuracy and damage. Armour-piercing flies slower, but has more mass and inertia, punching through more surface. Incendiary is slowest, but is filled with fuel, possibly setting your opponent alight. High Explosive is last, creating a miniature explosion on whatever it hits, doing damage, but not penetrating much.

Load them up, switch around your fire buttons, and get to the fighting! Fully-laden dogfighting airplane included; a Polikarpov Po-2