Well yes, on eboy your not going to find any magazine over ten rounds, that's their policy. However, at places like
gunbroker.com you will find the 15 and 16 round factory magazines. You do have to be a little careful on the 16 rounders, I've ran across one dealer that did not know the factory apparently are not importing the 16nrs and was selling the 15 for the 16... There are some available, I know, I have some of both... The new 15 rounders have ribs(?) running up and down their sides, and the numbered holes are on the back of the mags. The older 15 and 16's are smooth sided with the holes on the sides... I think I'm right on this, at least I have mags like that...

They are all Walther's.