I can't seem to find this info for the 1 Kopek silver Russian coins from 1672-1725. I know that these coins were struck very crudely and that the weight is more or less consistent, but it doesn't explain some of the drastic weight differences I've read online - anywhere from 0.68 grams to 3+ grams. Thanks in advance.
Because this was struck on silver wire, there can be big variance. I am not aware of any studies but you will need to send it for XRF to find out the purity of the silver content.
Do you know the purity of the silver wire? I would assume that would be more or less consistent. EDIT: According to the site below, the early 16th century wire coins have a purity of "'960' milessimal fineness". That's pretty high! http://www.metaldetectingworld.com/hammered_wire_silver_coins.shtml
As I know, last silver kopeks was released at 1718. Standard size - 13 mm, weight - 0,6 g. Silver .396.
I don't believe the purity of the silver wire kopek were that high. There may be the possibility that the Alexei silver kopek were of higher quality as this happened after the copper riot. However I am certain it would have been debased later in the years. I own one and it feels more like a billion.
Maybe that site I posted is referring to a different series of Kopeks than the Peter the Great era wire coins I was looking for. From the looks of it, I don't see how the 1 Kopeks can weigh more than a US dime, as they're roughly similar in size but the Kopeks are much thinner. So, I think the 0.6g-0.68g figure is correct. I'm waiting for mine to come in the mail but I can't weigh it without damaging the display packaging.
Mine is 10mm in length and 8mm wide, or an "average" diameter of 9mm. It's much thinner and smaller than a 1964 silver dime (which is 2.5 grams), yet APMEX advertises it as 0.12 troy ounces or 3.732417 grams (6.220695 times the actual mass, assuming an actual weight of 0.6 gram). Although some margin of error is within reason, 622% is ridiculous, especially when you look at all of the examples and can clearly see that it's smaller in every way than a silver US dime.