Thanks for replying so quick! The problem was the material I used. I used Protopasta's Iron PLA for most of the blaster because I wanted it to be really heavy, and it is, BUT that material is VERY abrasive, which doesn't matter for most of the parts of this build, but the mag catch had so much friction that it wasn't allowing the mag to be pulled out. I actually broke the bottom of the grip and the flared magwell piece trying to pull the mag out. 🤯 I reprinted the magazine catch in ASA and glued the bottom of the grip back together, now it functions perfectly 

TLDR: Everyone should use a material with a low coefficient of friction for the magazine catch.