I bought 5 like new G21 factory magazines from several GT members not too long ago. They are all recently manufactured and have the ambi cut outs. I recently took them apart to clean them and found three different finishes/colors on the magazine springs. Several springs have a dark bronze finish. I assume these are factory Glock springs. One spring has a matte silver finish. The other has a polished silver finish. Can anyone help me identify the manufacturers of the springs by finish: Glock, Wolff or ISMI? Or do Glock factory magazines come with springs with all different finishes? Thanks.