Heavy Copper LMC 3.278g

I tried using 10 of each copper VS zinc cents, randomly from the "year" piles I had sorted out.

Edit - Added one weight I missed and the averages of the groups of 10. I tried to find the ones that looked newer.

2010-2020
---------

2.500
2.501
2.500
2.531
2.500
2.498
2.493
2.548
2.483
2.492

Avg = 2.546

1970-1980
---------

3.075
3.088
3.218
3.080
3.075
3.083
3.133
3.152
3.066
3.098

Avg = 3.107 (3.1068)

I tested with 10 between 1970-1974, since I don't currently have 10 of the 1973 D cents.

3.048
3.081
3.064
3.134
3.100
3.114
3.110
3.081
3.112
3.031

Avg = 3.088 (3.0875)

Afterwards, I tried the "heavy" cent again and it came out to 3.276

Even if the calibration is slightly off, it's still over. From the side it looks a tiny bit thicker at the top, but that's about it.



I also came across a 1980 P dime that was 2.366 instead of 2.268, which is a bit heavy. 2.358 would be the maximum given the +/- 0.09, so that's only 0.008 overweight. This is probably plated, the face seems to come out slightly farther than a regular dime, but the back almost looks acid dipped. I wasn't going to waste peoples time with another topic already, unless they really wanted to see it haha.

The suggestion of "calibrating" your scale using items of variable unknown weights (coins) is probably not a great idea. Calibrating it with the known calibration weights that you have is the proper way to go which was what you did at first.

At 3.276 grams your cent is .036 gm out of tolerance, not "well within mint tolerances". So it is struck on a very slightly overweight planchet. Unfortunately it is not far enough out of tolerance to be worth a premium value. (Verly slightly out of tolerance coins are not that hard to find) Typically an over or underweight coin doesn't start to draw significant interest until it is .3 to .4 grams out of the tolerance range.