I know this is an old post but felt the need to comment about BH209. Don't get the idea that BH209 is not corrosive because it seems to shoot cleaner. It is just as corrosive or nearly so as black powder or pyredex. Clean your gun daily unless you like the look of rust in your barrel.
Respectfully I have to disagree......
Its no where near as corrosive as BP or pyrodex, not even close. Now BH does contain an extremely small amount of sulfer and I believe magnesium but, its no where near as corrosive as ANY other muzzleloader propellant. Until I went custom, I shot BH exclusively since I could get my hands on the first bottle when it came out. I've shot many thousands of rounds from different Encore platform rifles. Of those Encore platform rifles, ALL required fouling shots (hunting or target), as I may harvest multiple whitetail in one setting and, those whitetail could be at 70yds or 200yds. That said, I've fouled the bores with two primers, then sent two rounds to the berm on my range the day before whitetail season. After sending those two rounds, I'd load the third which would be my hunting load. Unless I harvested, those rifles would remain loaded from Nov. 14th through Dec. 1st, when I'd shoot that load and more, switching to long range targets. Clean the rifle's and repeat the process for the 10 day muzzleloader season. NEVER, not a single time, did any of my rifles have a speck of rust, inside or out. This was hunting during possible downpour rain one day and 20° and now the next.
Putting a cold rifle or wet rifle into a case, or bringing a cold rifle inside where its warm does more damage. At the end of each hunt, my rifle is wiped down and a light coating of oil is applied to the entire outside. When its cold, the case stays outside and remains cold. The rifle is put into the cold case before being taken into the garage. The cold case shields the rifle from the warmth of the garage like insulation. It warms gradually over night.
In no way am I saying BH can not be corrosive but, its no where near ANY other muzzleloader propellant for corrosiveness. Each owner should do what he/she feels is best for his/her rifle.