I had good luck with 90.7gr of H1000 & 300gr Bergers.
Berger bullets were too spendy for the end result..... I found I can get double the boolits and only sacrifice 1/4 moa at 300y by being less 'fussy' about boolit manf.
Currently I am shooting 250gr SGK @ 2780 97.4gr H1000.
I have found that H1000 is my favorite powder for the 338LM. It shoots 225, 250 & 300 gr (Hornady, Sierra & Berger) very well.
Cheers!