At 5280 they have 30 round MPX magazines for sale that they will "permanently modify" before they sell them. I asked what the modification would consist of. A pin? A limiter block? They would tell me at all what they intended to do. They just kept repeating that they'd "permanently modify" them. Given these mags are polymer I was concerned that they might be damaged in the process. Does anyone know what they'll do to them? Why wouldn't they tell me in the first place?