I use blackhorn 209, do a fouling shot before I load for a hunt, then normally don't discharge it or clean it until I shoot at game. I also leave it outside in a truck, garage, tent, etc, so it doesn't change temp rapidly and get condensation on it. If I am hunting in wet conditions, I usually clean it about every 2nd or 3rd day. Last year in Colorado, we packed in and hunted for 4 days in mist and rain. After 4 days, we changed locations and discharged our guns and reloaded. No problem with the guns firing (Omega and a Knight LRH). I would probably be more careful if I were shooting an open breech rifle. We use muzzle mitts over the muzzle to keep the rain out.

I was always more concerned with actually cleaning the rifle often when I used the other powders. But with BH 209 I simply run a couple of dry patches down the barrel and reload. BH 209 CAN attract mositure just as any powder can, but it is not corrosive in itself, so I have gone as much as 7-10 days with the rifle loaded/fired, etc without a thorough cleaning.