The mag catch on G&G guns is installed the same way it is on real steel. You press the mag catch button in as far as you can. On the opposite side of the gun, pull the mag catch out of the body far enough so you can twist it. I believe you have to twist it 90ยบ and it will pop out. Or unscrew all the way. Not sure what it is exactly on your gun. I've seen both styles so far (I have both).
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