Might have been me, but I know I'm not alone. I find R-P and REM-UMC to have significantly thinner case walls than other brands. When I used to reload on a single-stage press, I could easily identify every piece of it that got mixed in because of the difference in resistance. It does not grip the bullet tightly, leading to reduced pressures and an increased chance of setback. You could usually push the bullet further into the case with your thumb. IMO you'd need a reduced sizing die to make it load the same as other brands. I reload mixed brass, but I chuck out R-P and REM-UMC. Sorry.
If you keep it all together it will be at least consistent within the group, but I don't like the stuff.
