Rescue guns bug

So after the first time I got the rescue guns for Burning hearts UQ I put them in storage afterwards, then got another pair when I went on the quest again later that I can't dispose or put into storage again.

I discarded the one in my storage just fine but I can't remove the one that's stuck in my inventory even with it unlocked.

Any ideas that can get me my one extra inventory slot back?

Feed it to your mag, that's what I do