I want to buy a new base for a scope I am going to purchase. I am getting a nightforce nxs 5.5-22x56. I want be sure before I plunge into this. Ive settled on badger ordnance but am unsure of which one will suit my needs. I am shooting fclass f/tr and am thinking a 20moa bas will work well. what is the difference between the 306-06A and the 306-06. any other input would be appreciated.