I have a guess (Destiny)

by Kahzgul, Friday, October 30, 2015, 19:06 (3407 days ago) @ slycrel

I think the limiting factor wasn't your individual gunsmith rank, but actually the expected gunsmith rank of players who ranked up each week. So week 1 you could buy 1 gun. Week 2 you could buy 2, week 5 you could buy 5. Since he doesn't sell more than 5, that's it, you're capped at 5.

Some people were able to rank up more quickly by doing all of the rep stuff on the Tuesday that the game launched and then getting brand new rep guns the very next day (wednesday/armsday), which is why they were 1 rank ahead of the number of weeks that the xpac had been out for.