If it's a common date the counterfeiters use a base metal composite that will weigh around 22gr. If they are trying to pass a key date they might attempt to replicate the metal composition in a genuine Morgan and the dimensions. If they do you would not be able to tell with a scale. For this reason I would not buy an uncertified Key Date Morgan (1893-S, 1899-CC, 1884-S, etc.).
The majority of the non-key counterfeits are easy to spot for folks who look at them frequently. For many years they were using the reverse of the 1921 for pre-21 dates (look at the arrow feather design on a 1921 and compare to prior year dates). Other times they just don't pay attention to the details. I recently reported an ebay offering as a counterfeit. It was an 1878-S with the reverse of the 1879 (parallel arrow feather vs slanted arrow feather). It was being offered by a powerseller who guaranteed it's authenticity. ebay pulled the auction.
The majority of the non-key counterfeits are easy to spot for folks who look at them frequently. For many years they were using the reverse of the 1921 for pre-21 dates (look at the arrow feather design on a 1921 and compare to prior year dates). Other times they just don't pay attention to the details. I recently reported an ebay offering as a counterfeit. It was an 1878-S with the reverse of the 1879 (parallel arrow feather vs slanted arrow feather). It was being offered by a powerseller who guaranteed it's authenticity. ebay pulled the auction.


















