I am starting to see a pattern with some of my loads in 6.5-284. I live in Pullman, WA and do some load testing/shooting at a near by town,2500 ft). I travel to SW MT frequently enough that I do some of my load testing at longer distances at 4200 ft. I keep track of temps and conditions for every session. What I have noticed is that a load shot at the same temperature at 4200 ft and 2500 ft will shoot without pressure signs at 4200 and have a sticky bolt at 2500 ft. This has happened with H1000, H4831sc, and H4350. Does elevation affect pressures that much?