Bill: The used upper Sojorboy has is the older GDMR from AA back when they used the L/W barrels. Guess how I know?
Was L/W using the .295 neck back then? I thought they always used the .300 neck until the split-up.
This upper was sent back to Bill A. when new because the shells were hanging up when I was hand cycling it to make sure everything worked okay before I fired it.
If I remember right( this was 3-4 years ago at least), Bill said he filed off some sharp edges, I think on either the extractor or the bolt, I don't remember which.
Bill said he then fired it and everything worked okay. When I got it back, I fired 12 rounds of Black Hills ammo to sight in a scope on the upper and it's been in the safe since.
It fired perfectly for those 12 rounds.
I was also struck by the fact that both uppers were doing the same thing.
I hadn't thought about the magazine issue. Good idea to at least check.
I just thought I should jump in here to give further info so it may give you guys a better idea what the upper is and has been through. Hopefully it helps.