.338 and RE 33

Hello all, I have been loading for my .338 Lapua Magnum for a couple of years now it is a savage 111 Long range hunter 26" 1-9.25 twist I love it. I am working on shooting it accurately at a mile (this will take some time). I have worked up a load using IMR 7828 I am getting consistent 4 shot groups of 1.268 at 300 yards I know this will spread out with distance (work in progress) the 7828 is not filling the case up like I would like and I would like to get some more velocity, Has anyone been using the Alliant 33? I see that it takes more powder and I would like to get some input about the powder (pros or cons) before I buy and stat working up with a new powder. Thanks in advance.