I concur with Unique's 'uniqueness' for the .38.

In a 66-5 3.25" barrel and 158 - 160 LSWC, it seems, as I have read, that less than 4.5 contributes to leading (tho the bullets were swaged and I have since bought some Dardas hard cast 158.)

Overall, 4.5 seems to be fine, and any more than that seems unnecessary for target shooting. I tried 5 grains and saw little if any difference except the gun might have sensed it

I don't believe in loading any more than is acceptably accurate and clean in the barrel. Loading higher may not 'hurt' the gun but, IMO, it shows no benefit except to further tax the gun w/o good reason. I would rather save that for serious applications.