The factory ammo is why I hand load. 1250 is +p+ depending on who makes the ammo. Standard is 35,000 PSI, +p is 38,500 PSI and NATO is 42,000 PSI. The Glocks passed the NATO process but were too expensive. Unfortunately many 9mm+p factory loads barely are standard pressure. Velocities of 11,XX FPS with 115 grain. I've seen Hornady critical defense 124 barely over 11,20 FPS and other brands at 1200+ in the same firearm. I will say the Hornady had very good expansion and controlled penetration for home defense.
The 357 Sig is worse, USA sets 40,000 PSIas max, European standard is 44,200 PSI. American 125 grain factory ammo barely makes 1,250 FPS and European is very near 1,500 FPS. The Sig was designed to be equal to a 357 Magnum 125 grain from a 4" barrel and the European standard does that.