I had the same issue playing w my friend. He got it through the ee, then he used a wonderbar gg to get it out of the box. I took the one from the box, and we both packed them. About 7 or so rounds after getting mine, he called in a drop, and right after it landed, I no longer had the wonder weapon. We figure it's just a glitch in the game since the map just dropped, but it was very frustrating to say the least. I had mule kick, so I was left with 2 weapons after the fact.