I’ve always gotten consistent results using Alliant Power Pistol in my 158 gr LSWC 38 Spl +P loads. I use Speer +P manual data and have duplicated the velocity of Remington’s 38 Spl +P 158 gr LHP from a 6 inch S&W Model 10 (I wish that I still had that one) - 975 FPS as I recall. The load is 5.6 grs Power Pistol and Speer’s 158 gr LSWC - this is my favorite range/plinking load in my Ruger B/H 357 Mag with 4 5/8 inch while out in the high desert - has enough authority to keep me interested. Very accurate and doesn’t beat up my aged hands.
I also never noticed any unruly muzzle flash using lead/cast bullets and Power Pistol even when shooting indoors.
Please feel free to share your experiences with Power Pistol.