I have worked quite a lot with H4831SC, H1000, and Retumbo in my 6.5x284's. In a few different rifles with 24-26" barrels with 1:8 twist, H4831SC and H1000 produce very good accuracy but high pressure will start to show up around 2925-2950. In all these rifles Retumbo has produced the highest velocity, 50-75FPS faster, with no pressure signs, very low ES, and superb accuracy. Contrary to some postings, I have found 24-26" barrels to handle Retumbo perfectly. I have also found Federal 210's will produce approximately 50FPS lower velocity than Federal 215's when using Retumbo. I like H4831SC with210's for target shooting(2940FPS) Retumbo with Federal 215's for hunting(2970FPS). Bullets either 140 Berger VLD's or 142 JLK's.