A Nickel weighs 5 grams so it can’t be 30 grams light. The lower weight of this nickel is due to it being ground down. All damage, PMD.
If it actually pulls up on the scale with 25g of force, I think you need to skip CoinTalk and go directly to your local physicist. Did you find it lying on the ceiling above a CoinStar?
No it isn't, you are reading it wrong. 5.89 - 5.59 = 0.30g Just realized, I have that exact same scale.
Fair enough, it certainly does weigh less. However, someone taking a dremel with a grinder attachment can certainly remove that mass of metal easily. Here's an example of a nickel struck on a dime planchet. As you can see, the nickel is simply not complete. Your example has full rims and full details all the way through. If a coin is struck on a smaller planchet it will, by definition, lose the details on the edges. Yours is a fully struck nickel with post mint damage.
Most scales don't need that much calibration. You just have to recognize the decimal. 5.00 g is 5 g, not 500 g. If you want to check it, take 20-30 nickels and weigh each separately then average them and it should be very close to 5 (or 5.00).
Hope that helps. The only possible options for a wrong planchet for a nickel are: 1. Dime (as pictured above) 2. Quarter: As you can see, since the nickel is smaller than a quarter, there is a considerable amount of "extra" material on the rims. The ocin is complete, but rather weakly struck on the edges and rims. Again, your coin has the same dimensions as a standard nickel. At this point, the only reason why a nickel would have less mass is 1. thin, or split planchet 2. metal grinded off Since the strike is strong on both sides, it's not an erroneously thin or split planchet. With process of elimination, we have ruled out: 1. nickel struck on dime 2. nickel struck on quarter 3. thin planchet 4. split planchet After all those options are exhausted, the only possible answer is Post Mint Damage, PMD. When searching for errors, use Occam's Razor - unless you have a very good reason, the simplest explanation is usually the correct one. In the world of error coins, the simplest explanation is always Post Mint Damage. Until you can absolutely rule PMD out, there is no use in attempting to ascribe a mint error to any coin.
Are you saying the coin in your photo is a nickel struck on a quarter ? If so how could that be possible since a quarter blank is way too large to fit in a nickel coining chamber. I know that quarters can be struck on nickel blanks but never heard of a nickel struck on a quarter.