Running 200+ rounds through the firearm eventually loosens up the mag. It's important to consider reliability vs compacity. For instance, never putting more than 27 to 29 rounds in a 30 round mag. Jamming out the spring in your magazines could compromise the function of the mag when you need it...
The XDM elite 9 mm compact holds 15 rounds in the magazine plus one in the chamber. I believe this would be the answer to your question. I have the XDM elite compact in both the 10 mm and 9 mm. I got the 10 first, I liked it so much that I went back and got the 9 mm. Magazines are listed to hold...