I am in the habit of cleaning my shotgun barrels after use by (1) brushing out with a brass brush dipped in powder solvent, (2) running a cloth rag through the barrel to remove the loosened gunk and to dry the barrel of the solvent (usually requires two passes to get dry), and (3) running a cloth rag saturated with gun oil through the barrel to leave a light protective oil film on the barrel to prevent any rusting.
Before I use the shotgun I will repeat steps 1 & 2 but omit step 3, thereby removing the oil film from the barrel before shooting. Is it necessary to go through this step of removing the oil film before shooting the shotgun? It is a little bit of a hassle, and it seems a little unnecessary to me. What is your thought on this?