Remember each one is worth a minimum of say $20. So if you want to us the ones marked IS, or IA as these are common magazines. The IS is International Silver and the IA is for Inland. The IS, is a common replacement type not associated with any carbine maker and so is the (SP). Maybe the BW will also fit into being modified. How many do you need to make into 10 rounds and how many of the ones I listed do you have?