I have a Glock 23 that came with two magazines. I have since then purchased three more mags. My problem is that they are all 13 round capacities but I can only get, at best, nine in any of them. What's the secret to getting 13 rounds in them? Could they possibly be blocked for only 10 rounds? The first two mags. that came with the 23 are now 3 years old.