I have a friend who wants more mags for his 9. I told him that there may be a difference in mags depending on the model or serial number he has. Am I correct in my ASSumption? I sent him links to Ma's website, and to Midway for the 15rd Promags. I told him to stay away from the PM 10's as Ma's are cheaper with shipping, and the PM's may be POS's.