I had a TC omega barrel develope some light rust after 3 weeks. Our ML season is usually 2 weeks long where I hunt so it would get shot just before and then get cleaned after the last hunt. Seemed to work for me.
I have been using BH209 for the last several years. I normally shoot 2 primers to foul the clean barrel right before season then load. I keep a rubber glove tip on the barrell and use a spent primer in it when storing. Last year I confirmed zero and it was hitting so good at 100 and 200 yrds. I loaded it up or the season that started later that week with out swabbing. Shot my buck, reloaded and shot my doe with in 45 seconds and was done for the year. No rust or corrosion and the thing shoots amazing with 110 BH209 and Harvester PT Gold 300 gr. matches my scope BDC perfect.