Is your question about .357 +P ammo? As far as I know there is no SAAMI spec for 357 +P.
If you are asking about 38 special +P ammo, then you shoot as many of those as you can afford in your 357 revolver.
38 special +P is about 10% more powerful than standard pressure 38 special, but still significantly less pressure than standard 357 magnum ammo.
Shooting 38 special +P in a gun designed for 357 magnum is actually taking it easy on the gun- and the shooter too since the 38 special +P has less recoil.