Yaddio,
Annealing may help your brass, but the big accuracy deal with brass is necks that are consistent in thickness, varying not more than .001" at any point when measured all around the neck. Have not found recent Remington or Winchester brass all that consistent, so sort the cases for neck-thickness consistency before trying any handloads.
Also don't know if you're measuring the bullet run-out on loaded rounds. It should be no more than .005", about a 10th of an inch in front of the case mouth.
If you're not doing any of this, then trying different powders is pretty much useless.
