Can't help you with .38, but here's my receipe for .44 Mag and .45 Colt:
44 Mag
200gr. FP over 4.8gr Clay's, moderate crimp, Winchester large pistol primer, 1.560 OAL
45 Colt
200gr. FP over 5.2gr Clay's, moderate crimp, Winchester large pistol primer, 1.579 OAL
I shoot the 44's with two 7-1/2" SS Vaqueros and a Marlin 1894 Cowboy. The 45's launch from two Cimarron Thunderers and a Winchester 1892. The Clay's seems to burn cleaner than most. I prefer Winchester primers because, 1) the tray they come in lets me more easily dump them on to my flip tray with all of them facing the same way (I'm lazy), 2) I like the gold color in my cowboy loads
These combinations work for me.
stellarpod