In my experience light-screen chronographs (and in particular Shooting Chronys) are more accurate under cloudy skies.
Ramshot's data lists a maximum velocity of 2869 fps with one 180-grain bullet, the Hornady SST, using 60.5 grains of Hunter, at slightly over 59,000 PSI. That's from their 24" piezo test barrel.
Unfortunately, while they tested Hunter with a bunch of different 180's, they didn't test the Partition. But Partitions do tend to result in a little more pressure than average, and 2900+ doesn't surprise me, since I've seen it more than once from 24" barrels and 180's with Hunter. The pressure probably is a little more than 59,000, but so what? The only reason the .30-06's maximum SAAMI average pressure is 60,000 is really old rifles. In a modern rifle 65,000 PSI (the MAP of the .270 Winchester, among many others) isn't a problem.
