I have used the 300gr Berger and they shot well using H1000 (90.8Gr.) 2810FPS. But I wanted to get a little more velocity so I switched over to RL-33 and I started too low 96gr. up to 101gr. so I will try again at 102gr. and go up until I see pressure or get to 3000fps. I just got two boxes of Warner Flatline 256gr. I plan to shoot them this weekend at 1500,1760 and 2500yds. I was told to try RL-26 to get them to 3000fps.
I just ordered some Lapua 300gr and the Hornady 285gr. to test. I will save the Warners for a mile and past but the lead core projos for 1500 and under.
Currently using Peterson Brass Federal GMM LRM primers. Gun is a Tubb DTR with a 32in Bartlein. NF ATACR 7x35 Mil-Mil
Greatly depends upon your twist rate. I have a 1:9.4 twist and have used Berger 300 otm's with N570. You will have a higher level of performance using N570 over h1000. The fill rate is much better, and you will not reach pressure so quickly.
I have started using Cutting Edge Solids 265 grain lazers (single feeds), and have found they are a step above the Berger in ELR consistency. Same N570 powder .... More velocity 26" barrel (2950 fps)... Solids require a fast twist rate, so match your twist to the correct bullet. More consistent in the wind.... Overall, I Use the solids more than the Bergers. The Bergers are good, but I like the solid performance.
I also am shooting the 300gr Bergers out of my AI-.338LM. At the Nov. SWE ULR match i had hits at 1918,2120 and 2616 yards. I am using 90.6 grains of Retumbo Lapua brass 215m primer. Getting 2760 avg fps.
I am going to give the 33xc a shot and plan on shooting the Bergers.
Been using lapua brass in a pre-2013 sako trg 42 and 285ELD's at 2800fps with H1000. I'd like to try try rl26 and rl33 to see if I can get a bit more velocity. I ran a ladder with H1000 and had my magneto speed on my suppressor.