Small pistol primers were introduced into the 45acp cartridge because attempts to produce lead free Large Pistol Primers just didn't work out. There was a demand for lead free cartridges in 45acp so the manufacturers went to small pistol primers. As others have said pick one size and live with it. Mixing the two is just a train wreck in the making. HP38 and Win 231 is the same powder sold under different names.
Take Care
Bob
Take Care
Bob