I came across an old post regarding the .300 RUM and Retumbo powder. I'm working up some loads in my .300 RUM and I almost always see a faint ejector mark on my Rem case heads (shooting a model 700 SS, 26" barrel). I have never noticed any other signs of pressure and I'm trying to figure out if these marks alone are a reason to be concerned. All of my loads are below published max and low MV (chronographed) for the charge. One example is my load for a 180 gr Scirocco. I use 92.5 gr RL-25, Fed 215 primer, 3100 fps. Shoots well and shot this over 100 times.
I've read a lot of various opinions on pressure signs and the more I read, the more confused I become. Obviously my .300 RUM loads are a lot milder than the majority of shooters who post. I know it depends on each individual rifle, but if I lighten my load further I'm not reaping the benefit of a .300 RUM, trajectory-wise.