First off I'm new here so hello to all. Now this may be a dumb question but why is there a 10 round limit on a handgun mag? I don't understand the difference between one that holds 10 and one that hold 12 or 14. I'm going to do my PAL/RPAL in the spring and being new to the scene my buddy in North Carolina suggested as a starter to look into the Walther PPQ 9mm. I looked into it and realized the barrel is too short by our laws so I was looking at the PPQ .40 not to purchase just looking at specs now and the barrel is long enough but it holds 12 rounds in the mag. Can somebody explain to me why the extra 2 bullets makes this a prohibited weapon.