This has always annoyed me. After the 4th hive is destroyed on Nightfall, the Maverick vanishes, meaning you can no longer purchase it, until you get to the final Breeder fight.
Personally I love the Maverick, so I would LOVE to be able to buy it whenever I want, even if I do have to run all the way back to the beginning. I don't understand WHY it gets removed after a hive. You have not done that with the Ripper, and that gun (in my personal opinion) is rubbish.
I beg you, please allow us to buy the Maverick (charge 3k for it if you want, I don't care. Just make it so we can buy it when we want).