UPDATE: I have spent about 5M more credits since this post and have updated results - click here to see them! Ok, I promised to do a little experiment to.
A lot of people ask me how I have almost every weapon unlocked to level 10, including Ultra Rares. Assuming you don't have much unlocked yet, here's the most efficient,.
I'm frankly surprised that we managed to exceed the lofty goals of Operation Olympus this weekend, especially given the fact that I only had time to contribute a few matches.