Chuck: From a LE and legal standpoint, tell your Bro-in-law to only carry factory defense loads in his .38. God forbid he ever has to use it in that capacity, but if it was used to slay a cretin, even in self-defense, most prosecutors will hang you out to dry if it's found handloads were used in the homicide. They'll say "you made them
more deadly" (yeah, I know). Trust me on this one, I've seen it happen. Best advice is to carry what your local PD carries, usually Fed Hydra-Shock, Gold Dot, etc. for street carry in your PDW.
Whip up some good critter and plinkin' loads with Unique, have him stop at the store on the way home from the range and pick up a box of Speer Gold Dot .38Spl loads. He may thank you some day.