A rating for major depressive disorder

I submitted a claim for ptsd from mst in July of last year and after getting the records from my c&p exam, I know from what it said it is going to be denied. The examiner stated that I don't meet the requirements for ptsd but I do have major depressive disorder with A gaf score of 40. I was wondering can there be a rating for that and if so what is the normal rating of that disorder.