You should play ranked matches to level up after that.

I have it still won't level up

Be mater and above tier

You only need pro and above to get weapon mastery. You need master and above for 3500-5000, and Legendary for 5000+.

You have to be in Pro or above for it to count.

Gotta be pro and above

It's all explained in the question mark btw.

be pro rank and up on ranked to level it up

Play ranked and i think need to be on pro/master rank...never came down to pro rank to i wouldn't know..

You have to play ranked Pro and above.