The revolver is a Smith & Wesson Model 686, and the pistols are Glock 17s. (I’m going off the Internet Movie Firearms Database for this, since I’m terrible at identifying Revolvers, and it’s basically impossible to identify Glocks beyond their frame size and generation without actually looking at the slide markings.)
The Model 686 is a .357 magnum. The Glocks are 9mm. In both cases, we’re talking about firearms and rounds that will have no difficulty punching through plate.
Incidentally, I’m not seeing any marking identification for the Glocks in the stills. The 17 is a safe guess, and was probably the props used, but given we’re looking at an alternate history dystopia, they could just as easily be 10mm Glock 20s, which… yeah, you’re not stopping that with plate armor.
Historically plate armor did evolve to deal with bullets. But, modern firearms deliver substantially more power, and do so more accurately than the armor was designed to handle. To the film’s credit, it does show that the armor doesn’t actually stop the bullets. But, with the kind of firepower being used, V’s internal organs would have been reduced to goulash, and, I’m sorry, but, you just can’t
walk stagger away from that.