I've seen a few different tolerances for Kennedy halves online and have been checking mine as I come across ones that look thinner than normal. I came across this one yesterday and it is the lightest yet at 10.91g. Is that considered light enough to be outside of tolerance?
Half Dollar Weight/Tolerances: 11.500 g +/- 0.400 g = silver clad 11.340 g +/- 0.454 g = Cupro nickel clad 1873-1947: 12.50 g +/- 0.097 g 1.8 mm thick 1947-1964: 12.50 g +/- 0.259 grams 2.15 mm thick 1965-1970 & 1976: 11.500 g +/- 0.400 g = silver clad 2.15 mm thick 1971 11.340 g +/- 0.454 g = Cupro nickel clad;
If the thickness is not also outside of tolerance, I would think it is not a candidate for collecting. Thickness tolerance = 2.15 mm +/-0.102 mm
It is thinner than normal halves, that's how I decided to pull it out and weigh it. I don't have calipers to measure thickness though so I don't know how much thinner unfortunately.
Do you think this would work or do I need something more accurate? https://www.harborfreight.com/6-in-composite-digital-caliper-63586.html
If the coin was thin enough, it would have shown some weakness in the strike. The planchet would be thinner than the die gap tolerance.
I have one similar and it seems to work fine. I also have one like this which is especially useful if I want to measure inside the rim.
My Dad went to Watchmaking school in the 1920s/1930s and I inherited his watchmaking tools. This micrometer was with those tools. I see similar on eBay every once in awhile.
11.340 - 0.454 = 10.886. If your coin weighs 10.91, it's within tolerance by around .02-.03g (assuming the scale is accurate to .01g, which I wouldn't take for granted). If the planchet is off-weight solely because it's thin (which seems reasonable), the coin should be about 4% thinner than usual -- but that might not be accurate. A thin planchet might strike up a little differently, and the rims might be disproportionately shallow, which would make the coin more than 4% thinner.
