I've been shooting and cleaning S&W revolvers for more than 60 years. My practice has always been to fold a patch soaked with Hoppes (or whatever solvent you use) and rub it vigorously on the area between the top of the barrel extension and the underside of the top strap. This will remove powder residue, etc., from that area effectively. If the gun has been neglected for a long time (for example, if you acquire it used) and this area has caked on powder residue that has hardened, then more aggressive measures might need to be taken (bronze brush, etc.). However, if you faithfully address this area with a solvent-soaked cloth every time you clean after shooting, that process is usually sufficient.