I'm sure they don't. But the chamber walls of a 45 cylinder are considerably thinner than those on a 44 cylinder, hence they can't handle as high a pressure as the 44 cylinder. Put another way, the cylinder on an N-Frame 357 can no doubt safely handle 60,000+ psi but an N-Frame 44 with that same pressure would be a time bomb and an N-Frame 45 would surely kaboom after a few rounds at that pressure.