Power Pistol is my favorite powder in 38 Spl +P with 158 gr swaged or cast bullet - I use Speer 14 38 Spl +P data. 5.6 grs "PP" had duplicated for me Rem's 38 Spl +P 158 gr LHP velocity. 6.0 grs, max Speer loading, is a very accurate loading with more velocity (some chronographing obtained 1,075 fps+ in 6 inch tube using Hornady 158 gr lswchp - ref Handloader Magazine).

I also use it for a strong mid range 357 Magnum load - 7.2 grs behind 158 gr cast. Very accurate loading at this powder level.

I don't use Power Pistol in standard 158 gr lead 38 Spl loads - here I use Bullseye (3.5 grs) and HP38 (4.0 grs). Both very accurate.