I found US869 to the powder for my gun. 7828 could match the velocity and accuracy, but case life wasn't good- meaning I had to push it too hard. Found pressure too soon with Rl25 magnum and the other usual suspects. Never seen N570, but would be interested.
And you should be able to hit 3400 with that 30 inch barrel and 130 accubonds. I'm getting 3375 just fine in my 27.5 incher
