Anybody who collects gold or silver probably has a pocket electronic balance that weighs to 0.01 or 0.001 gram. I have two. They are less then $20.
Exactly.
Yeah, uncirculated coins (or very close to being uncirculated) feel different.
But these feel extra different.
This seems to answer your OP.
How does weighing a 1981 coin and a 2008 coin answer the OP’s question about 2026 coins?
I have a milligram-accurate scale, but I don’t have any 2026 coins to weigh. If anyone wants to send me some coins, I’ll weigh them. Heck, send me a whole bag of them just to be sure. 
Ok, just for a few more data points, I weighed some of the coins I have lying around:
| Nickels | Dimes | Quarters | |||||
|---|---|---|---|---|---|---|---|
| 1977 | 4.994 | 1967 | 2.264 | 1965 | 5.637 | ||
| 1984 | 5.016 | 1998 | 2.246 | 1978 | 5.598 | ||
| 1989 | 5.005 | 2004 | 2.274 | 1995 | 5.722 | ||
| 2005 | 4.931 | 2005 | 2.299 | 2015 | 5.721 | ||
| 2012 | 4.959 | 2014 | 2.288 | 2017 | 5.694 |
Sometimes weird coins get put into circulation. Here’s my story: About 1990 (important) I went to buy something from a vending machine, but it kept on rejecting one certain quarter. It looked OK, just worn, but because it didn’t work I set it aside and used a different quarter.
I got thinking about it, and since I had access to a lab with good scales and a micrometer, I got to measuring. This coin was much much lighter than any other quarter that I tested, and it was also much thinner. I had a hunch and dug a dime out of my pocket, and measured its thickness. They matched. Looking more closely at the quarter, I noticed that the date wasn’t fully struck, and it became obvious that the quarter was struck out of material made for dimes.
Since it was pre-internet (remember, it was 1990), I didn’t have any confirmation until later. But yes, that’s a minting error. Not particularly rare, it has a value between $30 and $100, so I felt lucky that I found it in change.
That’s not to say why the OP’s dime feels too thin, but maybe something’s going on.
Okay, try this-
Stats are the same.
But like I said- brand new coins have always felt different.
What I notice is a big difference in the feel of the milled edge of a freshly minted coin - a distinct sharpness of the milling than seems to wear off very quickly. The sharp edge feels like the plastic play coins my kids had back in the day, so a fresh coin has a certain fakeness.
Yes, good point.
Have you done a blindfolded test to see if you can feel the difference between new and old coins?
Also, if freshly minted coins are lighter, this could be the work of a counterfeiter with a very bad business plan.
Also, anyone, is there data on how sensitive humans might be to differences in weight?
Most coins are of such low value, it’s hardly worth counterfeiting them now.
We saw counterfeit £1 coins here, they changed the design to a bimetallic one.
A widespread tactic among fraudsters is not to counterfeit coins (that would indeed be too expensive) but to use similar looking foreign coins of lower value. For instance, the Brazilian one real piece, worth about 17 European cents, has the same bimetallic look, and approximately the same size and weight, as the European €1. It won’t fool a vending machine, but a careless human who gets it as change might well fall for it.
I thought that I noticed a 2000 quarter looking different— lighter?— than a 1974 quarter, so I weighed them, and, to my qurprise, the 2000 quarter was 5.65g , but the 1974 was only 5.47g! (still within tolerance, however). Worn?
1978: 5.56g
1980: 5.58g
1981: 5.58g
1994: 5.63g
1997: 5.63g
2001: 5.61g
2007 (dirty): 5.69g
2005 (Canadian): 4.47g
For the record, the change from silver was not a random impulse, as “switching it up” seems to imply. It was a recognition of the increase in the market price of silver, as the value of the coin materials was rapidly outstripping their face value.
Incidentally, for those who favor investing in actual gold coins to provide buying power in the event of economic meltdown should also have a few pounds of “junk silver” coins (pre-1965 US dimes and quarters) for smaller transactions.