Haz,
Every Ruger I own the manual states you can dry fire the gun.
My P32 manual forbids dry firing.
Since Ruger cloned the P3 AT it may be they were unable to tweak the gun to allow dry firing. With this, Ruger may have thrown away part of its "built like a tank" and "it's a Ruger" reputation.
That's not necessarily a bad thing but it will require adjustment on the part of the gun buying public. I can see guys who purchase an LCP dry firing the gun (even tho the manual apparently prohibits it) because they are used to doing it with other Rugers and they neglected to read the manual.