38's usually have the sights regulated for 158 grain bullets. 148 is close enough, but 125 is not. Try shooting some 158 grain lead bullets and see where they go.
The weight is the main thing that matters here, not whether or not it's "+P". (Jacketed vs. lead might also make a little difference)
"The only way to stop a bad guy with a gun is with a good guy with a gun"