You are incorrect. If you look at the links above you won't need to believe incorrectly anymore.
Stock magazines for the 22 hold 15 rounds. Stock mags for the 23 hold 13 rounds, but you can use the 15 round magazines, which stick out the bottom of the grip a bit.
Stock magazines for the 27 hold 9 rounds, but you can use either 22 or 23 mags, which stick out a lot.
FYI here's a pic of the three models. Note that the 27 has a non-stock mag extension/finger rest in this pic.
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