My Knight grew some brown schit under the DBC at the muzzle, possibly because the DBC was breached by the jag we used. I got it out, and the gun still shoots the same, but it gave me a bad time for a bit. So, I think it's wise to at least swab out the bore with a little break-free or something if letting it sit for more than a couple of days, even over a load left in. If only a touch is used and then wiped out immediately, shouldn't hurt anything. My new rifle is nitrided and much easier to unload and clean properly, so won't be left loaded more than a day or so.
