Found this on a reloading site, not my personal use.
I found Win AA Plus to be a good powder for .38spl Wadcutter loads. Very accurate and good load density (bulkier than other similar fast burning powders)
Use the same data as for the old Hod. Trap100 and Win452-AA. The AA+ was intended to replace the AA452, but as JW said, it was not popular with scattergunners who have gravitated to WST and Clays as powders of choice. WST is slightly less bulky and very similar in burn rate/applications.
In any case, it should not be confused with Win Act. Pistol (WAP), WAP is much slower burner. WAP was very similar to WSF, hence they discontinued it (WAP) in order to trim the offerings.
Also, one post that he used the BE data, but reduced it, started low and worked up with a chrono.
There are plenty loads for shotgun shells, what this was primarily intended for.