Simple question. Can I use the mag from a Shield 9 in my Shield 40? I found a 50 round drum for a 9 but haven't been able to find the equivalent for my 40. I'd like a drum for my 40 and was hoping that I could buy the one for the 9 and use it. I've found a lot of conflicting answers and don't want to drop $100 on the drum if it isn't going to work. Any input is appreciated.