Tony, a couple years ago I did the diameters/weights and Ferrous and Non Ferrous readings on most of my colonial finds and some early American coins and here is what I got from the Conn coppers I did. As far as results, well, the VT and NJ coppers all were pretty close to each other on readouts on the Explorer SE Pro, but the Conn coppers were rather varied. I know it is said they used at times copper that may have not been as pure as it could have been, not sure if that is rumor or truth, but seems I remember reading that somewhere, so I guess seeing that they do vary on the readings on my detector, that might be the reason. Corrosion is not a big factor in the readouts, that is one result I concluded from the study.....
YEAR WEIGHT DIAMETER FERROUS CONDUCTIVE REMARKS 1785 119.4 28.5 2 29 M.6.4-l 1786 94.2 28.2 5 28 M.14.2-S 1788 125.1 27.3 4 28 M.7-E 1787 110.5 28.4 2 29 M.33.1-Z.13 1787 124.5 28.5 1 29 M.33.2-Z.5 1787 113.0 28.5 2 29 M.33.8-Z.13 1787 126.1 28.1 0 29 M.33.17-r.1 1787-88 85.5 26.4 5 28 ? 1788 129.8 27.3 7 26 M.12.1-E 1786 151.0 27.8 3 28 M.5.8-F 1787 121.7 27.8 3 28 M.8-O 1787 133.5 28.4 0 29 M.39.1-h.1 small hole 1787 118.1 28.4 3 28 M.30-hh.1 1788 112.0 28.2 6 27 M.16.3-N