Island Beretta, I am going solely on memory here (and could even be thinking on an entirely different pistol), but IIRC from some reading I did many moons ago on these pistols, the design is delayed-blowback operation using roller-locking like the HK P9S, except it uses only one roller (compared to the P9S' two). Hence, a fixed barrel which allows the recoil spring around the barrel and the narrow slide profile. Unlike the rollers in an P9S which are on the left and right sides of the breach and engage a barrel extension, the Korriphila roller sits at the underside of the breach and engages the frame. I'm not clear on all the details, but I seem to recall this being the basic idea.
If I am wrong, someone please correct me. (for I. Beretta's sake, and my own).