OCD1, You are not "wrong" mentioning that 5gr of Unique is "kinda in the +P range" but I would submit that it is really in the standard velocity and pressure arena. Much of the current factory fodder is rather anemic and much of the data has been surpassingly so in the past 15 years or so. Alliant was particularly pathetic until the adquisition of Speer then suddenly their data became Speer data which is more realistic. 5 grains lands in the middle of max standard and max +P in their data........ However, much pressure tested data from Lyman and other sources spanning many decades has put 5 grains of Unique at standard pressures-often that is actually a tenth or two under max. Real world chronographing shows 5gr of Unique producing the long published ballistics of the .38 special (158 grain lead bullet at 860fps-6" barrel).Very little of current production ammo is matching the traditional ballistic standard. Some will say "better testing has resulted in charge weight reductions and the old ammo probably never delivered what was claimed".........but reading published testing spanning 8 decades has shown me that while not all of the factory ammo of decades past matched the advertised data, much of it DID.(Acknowledging of course that actual performance from revolver to revolver varies and some 4" guns are faster than some 6" guns with the same ammo) Given that tested data from the 1930s till now has shown 5 grains of Unique and 158 grain lead bullets to yield safe pressures while approximating standard performance for the caliber and that MANY past manuals often showed 10-20% heavier charges to be safe loadings, I am very comfortable with my own case measurements and chrono readings that indicate that 5gr Unique is a STANDARD pressure load with 158 grain lead bullets in .38 spl with every lot of Unique which I have tested.
Depending upon which powder lot I run through my measure using the same charge disc I get 4.8-5.0 grains and the variation in performance is small enough that I simply consider that charge volume as my standard load and label my reloads with the actually charge dropped (while finding that they will all shoot the same whether a batch is loaded with 4.8, 4.9, or 5.0)

All of which is of no great importance -but I think Bill is on the right track for a longterm satisfying .38 spl load that won't wear his revolver unduly but will deliver the goods.