Can anyone kindly line me out on the ideal size brush to use when cleaning the chamber of a 280 AI? Any and all intel about this is greatly appreciated.
You can measure your fired brass and choose a chamber brush a little bigger.
When I had a 7mm mag I used a 30 cal chamber brush to clean the chamber and it worked very well.
I used a nylon brush and it compressed quite well and had no problems with cleaning residue out of chamber and throat.
Edit to add: Amazon product ASIN B073WN4Q7F