Well, got a look at it today. It's loaded alright. The bore looked pretty bad, so I cleaned out a fair bit of rust using WD-40, patches, rubbing alcohol. Then I ran a brush down and ended up pulling out quite a bit of fowling.
Decided to leave in some WD-40 for a few days, then I'll patch it out, maybe even brush it again, if necessary. Will say after some effort, checked the bore and it looks pretty good! That was nice to see.
Meanwhile, removed and replaced the nipple. The one in there was rusted up pretty good, but after some cleaning, still screwed in and out fairly well, but for good measure a new nipple was installed, anyway. The snail/drum threads don't look too bad at all so I don't really see any safety issue with shooting out the conical.
The original RR is cracked, too, but I think replacements should be available on line. May have a trip to the range on Saturday, unless I manage to get out deer hunting again.