I've done some testing with the 300 Ultra and 220gr SMK's and 178gr A-Max's using Retumbo and noticed pressure signs to be pronounced at less than even 65,000 psi on the Oehler 43, ejector marks even started showing at 60,500 psi with the 220's at 88gr and 2930 fps. I am getting the same velocity as I am with RL25 with a couple more grains powder of Retumbo than RL25. Their are no pressure signs with RL25 at even 70,000 psi and velocity is much higher too, but the Retumbo causes stiff extraction and ejector button marks on nearly every load from where I started. What I don't understand is, the peak psi is lower but causing brass to flow into the ejector bore??? I actually watched for psi signs to come quicker because S1 and some others said they showed signs earlier than RL25. I had expected the psi to jump high as well but it was way low when it showed clear signs of psi??? My first impression of this stuff is it won't work out like the RL25 has been. All my loads are temperature stable from 10-45 degrees so far with RL25, we'll see how they do at 70-80 deg this summer. Anyone have observations along these lines with Retumbo?