In years past I have used my hunting load for a fouling shot. Spit patch. Then reload. The gun stays outside. If I haven't had cause to fire it again after two days, I take it apart and do a thorough cleaning.
This year I switched to Barnes Expanders. They're pretty pricey so I hate to just throw one into the bank. Figure I will use one of my old Buffalo Bullets for the fouling shot (still with my standard 100 gr 777).
Not wanting to wake up the neighbors at 0-dark-thirty or scare game, I've always been looking for a quiet fouling shot. My answer has always been to just foul it the night before the hunt (away from my spot). Randy Wakeman offered an alternative that I am going to try. Just use 40-50 grains of powder with a sabot, no bullet. He claims it is much quieter and will still adequately foul the barrel.
Bim, there's a difference between running a few patches down the bore and really cleaning the gun. A couple patches in the field are no problem, but there's no way to do a complete cleaning while in the field. I think Michiganiac was talking about a fouling shot after a thorough cleaning.