A warm welcome is extended to you Aaron "The Pinfire Collector".
Expertise in specialized fields of collecting, is a great asset to our knowledge of history, and identification of finds.
From my own experience in searching sites from specific decades, 1850's, 1860's, and 1870's, I've noted that we only begin seeing a few pinfire shotgun shells found on occasion in 1860's sites, and then into the 1870's. By the 1880's the center primed shotgun shell became the more prevalent product.
There is only one type I have seen without makers mark on it and you can debate if this was or was not in the Civil War the photo is below... The only way to go about telling if say this photo below is from the Civil War is going by the corrosion on the artifact, if you say that this members pinfire pin is from the 19th century and civil war then I do not know what to say other then the fact for it being in the ground for 150 years must have not gotten no corrosion what so ever from tropical soil in Hawaii.
HutSiteDigger,
Your posted photo of a pinfire shotgun shell, "without makers mark", clearly shows the raised letters of EY and B above the 12.
This is certainly an ELEY BROS raised mark stamping on this shotgun shell.
Furthermore, corrosion on artifacts is caused by a great number of variables, and cannot be used to accurately determine the age of items. I've seen brass items from the 17th century, in hand and freshly excavated, that looked nearly as though they were lost well within my lifetime. On the other end of the spectrum, I've seen items from the 1960's corroded to the point of near unrecognizable condition. Moisture, soil minerals, acids, salts, and other factors, all affect the condition of metals buried beneath the surface of the ground.
Certain areas of Hawaii are very dry and almost desert-like. Items from the 19th Century, recovered from arid desert locations, can hardly be compared with items recovered from the forests in Virgina, with predominately acid rich soils from deciduous hardwoods, or from farm fields laden with fertilizer.
CC Hunter