Why don't firearms have the class rating on them in the inventory?

So the question I have is why don't guns have the class rating on them for the ammo they take? I can understand why shotguns and bow wouldn't, since they can take different ammo for a wide range of classes. However, rifles and handgun are caliber specific and therefore have a specific class rating. I just don't remember what class each caliber is when I looking through my inventory. This is even a bigger issue for guns I don't use often. I sometimes what to grab a gun I don't use often to change things up, but that is frustrating when I don't know the class each gun is. Am I missing something or is this something other experience too?