Were you using HCD (Horizontal Corrected Distance) from your range finder or true distance? You mentioned a 2-degree slope, so I am wondering if that was being accounted for twice. That would make your POI high, but I am not sure if it would account for that much without doing the math.
Can't go wrong with 300WM for your stated purpose and the wide availability in factory loads make it versatile. I personally went with the 300PRC because I wanted LR hunting and ELR target shooting with one rifle.
On the 300PRC side; recoil would be stout with a lighter weight rifle, but I...
Will give Magnum a shot on my next order. LRT has been great for me and meters just as well being a ball powder.
My only concern is about temperature sensitivity in both, but I haven’t tested it.
What length barrel is the Christensen Arms?? Your numbers are way above the published data from Hornady which shows 76.8gr of H1000 pushing a 220gr at 2800 FPS.
Powder Valley had the best price when I ordered, and they were running a no HazMat fee promotion at the time. I haven't seen anyone waiving the HazMat fees since the pandemic buying started around March.
Western has published data http://blog.westernpowders.com/wp-content/uploads/2019/10/300-PRC.pdf
This is what in worked from for LRT. I am getting 2930fps with 225gr ELD-Ms from a 26” barrel.
I haven’t tried magnum, but I’ve seen around the net where others have.
I don't have personal experience with H1000, but it appears to be just above Ramshot Magnum and RETUMBO in burn rate. That load is right in the range for the published data for 225gr ELD-Ms and in the same barrel length. I would not expect unburned powder to be the problem given the published...
A chrono would help you validate if this is indeed the issue. It sounds like you tested at both 100 and 600 yds. At 100 yds it would be very difficult to tell the difference between charges in a magnum cartridge they are going to be so close together at that range. At 600 yds you should be...
One possible cause for this that a chronograph could help pinpoint would be incomplete powder burn. If you are using a very slow powder like I am in this cartridge you may hit a velocity "ceiling" where the powder is still burning after the bullet leaves the barrel. Depending on barrel length...
100yd zero with 20 MOA rail.
With my setup (Nikon FX1000 4-16x50SF) I could have probably still zeroed at 100yds with a 30 MOA rail; which would have given me more adjustment, but with 22 MRAD of adjustment, I should be able to get the 300 PRC to 2000yds and slightly beyond.