This was a P365XL model, that has a 507K mounted. Runs completely with all +P, High quality defense ammo I tried. Tested with GDHP, (40 rounds 124gr +P, forty rounds 124gr Shorter Barrel, twenty rounds 124g Conventional, 60 rounds 147gr normal), sixty rounds 135gr +P Critical Defense – all of these had zero malfunctions. Also functions perfectly