They are designed to push the rounds down slightly when clipped on so that the feed lips aren't holding all the tension of a fully-compressed spring with all rounds loaded. Just curious - how much are they asking for just the cover?They sell them separately now. I wish they came with them still though since I keep the mags loaded and stored. The dust cover keeps the pressure off the feed lips. Might not be a huge deal in the short term, but in the long term, it should keep the feed lips from deforming.
They are designed to push the rounds down slightly when clipped on so that the feed lips aren't holding all the tension of a fully-compressed spring with all rounds loaded. Just curious - how much are they asking for just the cover?