Brand new player, weird issue with unloading a mag in the character screen.

I just started a few days ago and have slowly been learning the basics. I have killed 2 pmcs now and the one I just killed had a mk17, the scar looking rifle. There is a mag in the gun in my stash, it says 6/20 at the bottom right too for the ammo as well, but I can't unload the damn thing. Right clicking and pressing unload says Can't find a place for the item, and same if it is equipped. I just want to take the mag out to salvage the ammo which I did to the sr25 of the first pmc I killed and got m82 I believe. Is there a reason why I can't do it to the mk17?