Sorry all, I slipped into Engleutsch again. NIPPLE is what I meant!

The message was, if even a part that is supposed to be regularly removed becaomes baked in hard pretty quickly, then it is extremely unlikely that a breech plug (or indeed any threaded joint) is easily removable after 150 years.

Hence the conclusion that someone probably had a good reason to do so fairly recently, and it would be a good idea to check the serviceability of the barrel.

And in spite of my linguistic confusion, I am happy to see that you also agree that the plug should not be easily removable.