I just bought a DPMS LR-308 4 round mag for my LMT MWS and the mag won't lock in. When I remove the upper and try it locks in just fine. I tried with a round in the mag and its the same story. Any ideas what the problem could be?
Hard to say for sure, but it sounds like the top edge of the magazine is hitting the bottom of the upper, like maybe the mag well is not perfectly lined up with the upper. I had an out-of-spec ar15 lower once and it caused mags to hit the bottom of the upper in the front. That's what made me think you may have that problem.
I would take the upper off and put the mag in and then compare it to another one that you know works in the same way with the upper off and see if you can see any differences.
I tried with the bolt both opened and closed. Figured out the follower was hitting the bolt. One good whack and in it went. Now to file the follower just enough to clear with no problems. Thanks for the input.
