This was discussed on another medium recently. Someone mentioned that repro Magpuls use softer rubber and are easier to fill MWS mags with than real Magpuls.
If you're looking to mitigate bolt lock issues, just to advise that there is a few ways you can mitigate this with a bit of tuning. For instance I have a RS Magpul BAD lever, stock catch plate. But have a reliable bolt lock due to gas choice and buffer tuning.