I have a 1951 d that is the size of a dime. it weighs 3.00 g and when stacked on a dime it is the same round
back in the 50's and 60's kids would grind down cents because they could use them in a coke machine to get a soda. another possibility is that it has been soaked in acid.. can't really tell without pics Richard
If it was "ground" down to the size of a dime it would probably weigh somewhat less than 3.00 grams and the grinding would be rather obvious, as it would destroy the rim. How thick is it? That's the key... if it's a shrunken cent it would be thicker than a normal cent, but otherwise look OK.
Also how wide is the edge compared to another pre-1982 cent. If it is wider it is most likely a "dryer" coin ( one rolled around and around in a dryer drum) that has been compressed downward into that size, which is a common cause. A photo would help. Welcome to the forum! Jim
it is not acid treated and it is red unc. looking at it from the edge it is bowed inward not outward like being smashed. it is also 1 percent off center
It does appear slightly undersize. The older Lincoln cents shrink quite well, and that's what this one appears to be. Coins can be shrunk various percentages of full size, as explained here: http://205.243.100.155/frames/shrinkergallery.html
after checking this site I so see shrinkage however looking at the coins that were shrunk, they have a worn look to them and a distortion to detail. My cent has none of that. It appears to be struck on a foreign planchet. not sure where from. what foreign coins were struck here in the USA during 1951. I believe Philippeans. not sure
If it were stuck on a smaller planchet, it would'nt have all the words/date etc...the die dosen't shrink if stuck on another planchet.
how about if it were on a slightly smaller planchet or a softer material. there is no raised rim from 6-12 o clock on the reverse. similar to that of an off center
Here is the PDF of mint production including foreign coins. Use the search button within the PDF to fidn the foreign section . Too much for me , The mint doesn't make it easy, and then you need to look up each possible planchet to see if it matches size and weight. http://www.keysquality.com/downloads/domesticforeign.pdf Best of luck Jim