I've heard various opinions and I don't have anything that I use those powders for experience. I heard the same about Reloder 19. I use it for my 160 gr Partitions (Elk Load) for my 270 WSM. I reloaded in Arkansas and Killed an Elk at about 9500 ft in Wyoming. The load seems to maintain it's consistency. I'm getting a Magnetospeed Chronograph for further investigation.Is RL15 stabil?