So a friend of the page was asking about M1 Carbine magazines and what the fit would be like in more modern pouches. Thought maybe some other people would be interested in it too.
The 30 round magazines fit 3 facing forward and 2 sideways in early style MOLLE mag pouches. They are pretty snug with 3 and a bit rattle-y with 2.
The 15 round will fit 3 forward and 2 sideways in the grenade pouch and still be able to snap. 3 is snug and 2 is loose.
If I had to do the same I would recommend using the later MOLLE mag pouches with the elastic. It allows you to hold them in place like regular AR mags. Maybe fold the velcro down or a little better access since they’re a little shorter than AR mags