Been playing with some new loads and I'm having pressure issues. I'm shooting a .338 - 300 RUM with a pretty long lead (.212", lead + throat .4755"). My favorite load has been 107 grains US 869 with a 265 grain Barnes TTSX (LRX, MRX, whatever they decided to call it). Great load but I wanted to try H1000. I extrapolated my starting point on the load based on bullet weight and decided to try 97 grains H1000 with a F215 primer. Resulted in an extractor mark but no sticky bolt or measurable case web expansion. I tryed working it down and even dropping to a standard primer (maybe a mistake) but pressure signs increased. At 93 grains, standard primer, and 30 degree powder temp, the bolt was sticky and I had a case nearly separate. After thinking about it, the only extractor marks I have gotten during hunting situations with my old loads with US 869 and F215 primers or Retumbo and F215 primers have been on days below 30 degrees. Now I wonder if I might be undercharging everything. I have very few guns that shoot loads that can be found in a manual...or even online. I've figured quite a few loads out with a calculator without issue. This one's got me concerned. I'm a little scared to go up or down with the H1000 load without more info. Anyone else with this experience or a known H1000 load for this bullet?