I was doing some thinking -- in the beginning when I got my carbine, it came with an aluminum magazine. I had questioned in the previous post if your were, only because the finish is coming off.
When I had mine, there was a serious issue with them not holding the rounds securely during recoil and bolt operation. I cartridge would flip up, and the bolt would not engage the rear of the case -- riding along the case body. AND I did have jams.
You said that you had deep scratches in you cases. So did I and I had forgotten where they came from. You jogged my memory. Eventually, by the way, the cases failed along those deep scratches -- split.
Bushmaster replaced my aluminum mag with a SS one. In fact, near the caliber stamp on the mag is has SS.
Just a thought. Can you gain access to another magazine?