Theoretically a non-whale should be able to acquire at least MLB Sol's gun in 3 and above tower events: 3 if they perfectly clear all missions and get max points for the SSR LB set, and above accordingly.

And then there's a matter of randomly pulling Sol's gun again from the jewels, but I'm sure non-whales don't want that. Then again, the question is which kind of weapon should we really focus on MLBing.