Scale unlocks based on account/class level. same as what the previous poster said but expanded apon. early on when you are new you want to be unlocking things quickly like attachments so you dont feel left out and so that guns are easier to use. late game however it should get longer to unlock guns to incentivize play and objectives and teamwork more. I've unlocked most of the guns and ive had the game for about a month, we need more progression, or slightly slower late game progression