This has probably been posted many times by many many players. Anyway, I feel like sharing it.
The image shows bullets on a graph depending of its penetration and flesh damage. There are no shotgun cartridges included (probably will make another sometime). The differents calibers are shown with a different colour, and symbol type follows a simple division (pistols/smgs, assault, sniper).
I try to keep it up to date with each new change. Hope you like and find it useful!