I’ve tested a few loads comparing velocity using Rem 2 1/2, CCI 300, and Win LP only in 45ACP. Rem 2 1/2 gave the top velocity by 25-40 fps with Wib LP being close to the RP. CCI showed the least velocity by 25-40 fps but very consistent. This was a small test with two powders. I’d say they are interchangeable unless you’re loading max charges. You will see some data that list RP 2 1:2’s in magnum pistol loads.