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The Bren gun took 32 rounds in a magazine. This 48 round box could provide 1 1/2 magazines or 3 magazines for two 48 round boxes.
However, most of us loaded 30 rounds in the Bren and Sten Gun magazines to prevent the possibilities of jams.
Also, the 9mm ammo was packed 64 to a box, or two magazines worth.
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