. . . the area around the nipple gets a lot of attention when cleaning, and even when shooting.
There is always some blow-back of fire up the nipple and off the nose of the hammer. The weaker the hammerspring, the more blowback. Some combinations of load, nipple wear and hammer seal will allow enough backwash to set the hammer back on half-cock.
All the residue around the breech might not be from the nipple.
I have suspected the hammer spring, although it "feels" right.
When you say "All the residue around the breech might not be from the nipple", what are you suggesting?
I've always suspected the little grren monster inside the cap to be the culprit. There are times, when the light is just right, I can see "something" that appears to be very small white specks that wipe right off...that does occur most often with Magnum RWS #55 caps..I think. Although I've seen it with others as well. Can you see Mercury Fulmate, or whatever it is that the "caps" are loaded with, once the cap has been fired???
Just a bit of trivia...It seems the percussion cap has experienced the shortest life of any the ignition systems.
Designed around 1805 / 1807 (depending on who are reading) by the Rev. John Forsyth, it did not come into acceptance until around 1829/1830 with the flintlock being the "major" ignition system due to the many problems encountered in the manufacturing of percussion caps.
Then about the time they get the problems all ironed out, a new invention came along. The end of the percussion era is said to be about 1864, giving the percussion cap a life span of about 30+ useful years.
I honestly feel that MORE percussion caps are being manufactured, and sold today than ever in history. :hmm:
Simply because of economics.
Do you think our early frontiersman fired a cap, or two, prior to loading and shooting? I don't.
Russ