I believe the mags are supposed to be 10 rd., but the aluminum slide doesn’t stay locked after the last round. An extended mag follower is available that retains the 10 rd. capacity but extends to hold the slide back after the last round which can prevent damage due to dry firing if you lose count.

Sorry, should have followed up. Stripped both mags and found injection molding squeeze out on both bottom of follower and top of plug - cleaned both up with a file, cleaned, re-assembled and both took 10 rounds easy. Have since replaced followers, springs and plugs to extend mags to 15 rounds with slide hold open on last round.