Are you shooting the .40 at "major" or "minor" power level in IDPA? That will make some difference in recommendations for best powder and bullet weight.
You could also go here, join tht forum, go to the reloading section and ask the IDPA shooters:
http://idpaforum.yuku.com/ .
One thing to avoid is Remington brass. It has a tendency to be thin and that can make bullets loose in their cases. That may allow bullet setback from the feed cycle, which can drastically raise pressures, potentially damaging the gun and you.
SL1