I think some are confused w/fouling a barrel and corrosion. You can foul your barrel w/ a #11 cap or 209 primer and in no WAY cause corrosion when you drop your powder load down thisprimer fouled barrel. Corrusion only happens when you explode the BP or substitute to cause the causticreaction or as already been pointed out, wet powder. With that being said I have always shot clean barrels and swabbed totally clean between shots. This season howeverI had some trouble w/my X-7 Omega and I ended up dirting the barrel w/a 209 to get my Sabertooth load where I wanted it. By the timeI figured out the clean shots were 11" high I was all sighted in and didn't wantto change anything for the season. I hunted in heavy snow and rain conditions of 17 degrees up to the low 30's. What I NEVER do is bring my firearm into a warm enviroment unless in a padded or foamed gun case and would let it warm up to room temp for 12 hrs unlessI were to clean it. I have followed this rule for 7 NY seasons and NEVER have had a misfire or delayed ignition. I have always covered my barrel ends when hunting by useing finger cots or the cut off ends of those harbor freight blue gloves. I originally started out w/ ballons but the were not very strong and split easy. I always keep a 5 on hand, hehe!

But to be sure if you do shoot a fouling shot w/a true powder load and don't clean it for a season, kiss that barrel goodby...

BTY, I didn't fire my BP rifle this season for the first time in 7 yrs.. None of the deer racks I saw were outside the ears and 8 point or better. I hunt BP through the regular firearms season whenall I hear is BOOM BOOM BOOM BOOM. It just blows my mind to hear so many shots day after day. Either they miss one heck of alot and need some range time or are mameing tons of game. I only found one dead doe that the crows were feasting on.
When I shoot everyone comes to see....KaBoom, dead deer....
I have numerous high power modern rifles that hold very tight groups that I don't shoot,JUST love BP.....
Thanks,
Steve