Triple 7 is every bit as corrosive as Pyrodex if left in your barrel.... just takes longer for the corrosion todo the damage Pyrodex does. I've gone two weeks without cleaning my 777 fouled barrel.... an aftermath of several shotswith anice weather pattern.... then kept the rifle in an air-tight,foam, hard-shellcarry gun case.

The longest I would trust my Pyrodex-fouled barrel under the same conditions was three days.