Cayugad,
You should have been a private investigator.....heck maybe you were or are. LOL
If he can get the nipple off with Kroil (not Kroll) see url: http://www.eastwoodco.com/shopping/product/detailmain.jsp?itemID=11344&itemType=PRODUCT&a mp;RS=1&keyword=kroil

I'd think that a person could use a small water pickto flush out any powder that could be in the breech area, you could use an air hose too to aid in this process. After a good cleaning, I'd think that you'd be pretty safe that the main charge had been cleaned out.It might be a good idea to do this a couple of times to be certain it washed out. Dry it all out and then trickle a little powder down the nipple hole and touch it off with a #11 cap. Taking all the safety precautions mentioned in above posts.
I wish I had the barrel to play with....dang.