The question I have is this: Is your AR weapon skill (not the class skill, but the individual weapon XP) already maxxed? If so, that weapon won't provide you any more bonuses to your assault rifle CLASS skill. May be something as easy as switching weapons, and from what I've understood, there IS a way to remove the XP from a weapon (and the small bonus it gives at full xp) so that it keeps working, but for the life of me I can't figure out how.
The individual weapon XP is the Xp bar directly under the weapon when you have it highlighted in your inventory panel.
So is it impossible to rank certain weapon skills as a certain class for instance as a outlaw can i not rank my AR skill?
Take the word 'class' out of your vocab, there are no classes. Your starting Origin only denotes your beginning appearance, starter weapon, and starter outfit. After that you can pick up and level any weapon you want.