I believe briang2ad got it right. The gen1 (P07 Duty) had some frame spread tendencies due to the polymer formulation. Changes made to the later frames (front serration frames) improve the rigidity.
Prior to the present NJ fiasco, I had some 16 round mags, and kept my P07 loaded 16+1, and never had any problems. Thanks to Phabulous Phil and the rest of NJ's Phreedom lovers, I no longer have to worry about those problems. LOL