You could make the p mag anything you want under 20 rounds, remove the bottom cap, insert a trimed piece of wall corner protector, and if your laws are like mine, drill and install roll pins, when it holds what you want. If your in California, you may want to trim off the bottom of the mag where it says 20 rounds If you shorten the mag, its better to trim a little off the spring. I made 10 rounders, 5 rounders, opps and a 11 rounder. need to take that one back apart and fix it. <thumbsup>