Obviuosly it is a "duh" question, but each of us has to be told individually so we don't make a mistake and get hurt. The amount of shotgun/pistol powder you put in the case is a full load for a shotgun and very powerful. All of that corn meal has the weight of a decent sized bullet. Toilet paper wadded up does not disintegrate inside the barrel but flies out of the barrel in a compressed wad. If it should hang on some of the ports and cause a constriction then you have 20+ grains of Unique pushing about a 150 grains bullet made out of cornmeal. SOMETHING HAS GOTTA GIVE.
You might can get by without taking off the brake but then why risk a $5,000.00 custom rifle
When I fireformed cases up on Wildcat Creek I was ashamed of myself because there was little balls of toilet paper littering the place and making it look trashy. Also there was cornmeal sprayed all over the place.