Bul Armory Cherokee 9 mm pistol. Comes with 2 magazines, advertised as 17 round capacity. Out of the box neither will hold more than 15. I can force 16 into one of the mags, but the round doesn't sit properly, so I suspect a failure to feed would occur if I left it.
I have never had a new magazine fail to accept the advertised capacity, although a tight fit does happen sometimes. Is there an expected break in period for magazines by some manufacturers? That is what the seller says.