I have an older 39 series pistol, a 3954 to be exact. It came with one 8-round mag with an extended floorplate, and one 7 rd mag with a flush-fir floor plate. I prefer the flush-fitting one, and want to purchase a couple of spares, but can't find any anywhere. Any thoughts? Also - it doesn't appear that I can buy the protruding ones and simply replace the floorplate. Thanks.