It’s a bit hefty as it’s all the guns in War Thunder (air, tank, ground), but it’s oganised by the gun type/model. In the link then is the info for all the rounds it can take in the various belts.
Have in mind that the muzzle velocity in mixed belts is determined by the first shell in the belt - that means that even if other ammo types have a higher velocity: If your first round is the “slowest” all other projectiles will have this “slow” speed…