The bolster clean out screw is not as important as we are lead to believe. A lot of rifles no longer even have them. If they are there, I do take them out if they want to come out. If not, leave them alone. When you give the water bath it increases the water and pressure which means a cleaner barrel and bolster for that matter, with it removed. When done, I like to make sure the barrel is dry, but I then take some alcohol and pour that into the nipple and bolster hole. Let it sit in there a little and then with a fuzzy pipe cleaner, push that into the different nipple and bolster holes just as deep as you can get it to go. That is basically drying and clearing the channel all the way to the chamber where the powder sits.. I then like to take an air compresser and blow air through there as well. This dries it as well and makes sure there is nothing left from the fuzzy pipe cleaner. A little anti seize on the threads, and then carefully so you do not drop it, replace it. It will then come out nice and easy the next time.