My methodology: I put a handful of pennies (I try to go for about 50 at a time) in a 1-gal flat storage container, shake, and scan for dirty coins to pull out. If I happen to catch a wheat, canadian, S, or other oddity, I pull it out. I then tilt it to make them go to one end and flip them and scan again before dumping in another bucket to be Ryedaled. Wheats, Canadians, S, etc - these I only do a cursory scan for. I am primarily trying to keep garbage out of the Ryedale. Dump, scan, flip, scan, dump: this takes about 10-15 seconds per handful.
So the first bag had the normal 20-25% Cu, dozen or so Canadians, half dozen or so S, etc.
Next bag had 40 dimes and the usual assortment of wheats (a dozen or so), Canadians, S's, etc and a higher percentage of Cu.
The next bag had no silvery stuff at all but had only about 25 zincers. The rest was Cu.
The next bag has about 45-48% Cu, as scientifically ascertained from eyeballing them sitting in identical 1-gallon ice cream buckets. Weights: Zn is about 24# while the Cu is about 25# and both together look like 48.5#, all on a bathroom scale. Of course, Cu is heavier. Going strictly by volume, it looks like it is 45-48% Cu.
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Anyway, not too bad I think, after having been out awhile.
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If I had the cash, I'd go back and buy up all the bags at my source.
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Well, off to dump Zn.
-james