I redesigned my own Nerf stock, the old one was a little loose and could slip off while playing with it, this one I put two slots in it that line up perfect with the slots on the Commander, it is solid now and a tight fit, it is supposed to be a tight fit!
Also, I thought it would be cool if I worked some extra ammo slots into the stock, these are also a tight fit so they don't fall out in the heat of Nerf battle!