Like above, take mag box and follower out from a centerfeed. Then shim it with cardboard, and tack with hot glue in place. Remove cardboard, check fitment, and run hot glue along top angles of magazine to fit permanently. But, don't run so much down in that you can't take it out easily later. I did it and it has held fine.

The staggerfeed opening in the stock is larger than a centerfeed.

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