Before I figured out that I could get the first shot out of a clean barrel to hit the same as subsequent shots, I was going afield with a fouled barrel as well. This was recommended by the tech folks at Barnes about three or four years ago. I have left my stainless steel T/C Black Diamond fouled for six days without ill effects. This was, however, in the dry September weather of Colorado.

Since then, I swab my barrel between shots with diluted Windex (with vinegar), then a dry patch. It hits the same as the dry barrel shot. No real need to tempt fate with the fouled barrel.