Beast- as we have discussed, your Mom will need to work out how and if she would have a gun in the house with the problems your stepdad has legally- and as pointed out, YOU have 7 years before YOU can make a purchase.
Folks- Beast is a minor, and his stepdad has a felony conviction. While your input is well meant, without the backstory, the advice does not work.
Beast- hardest thing in the world for a teen to do. Wait.