I copied and pasted this comment from a previous topic last year. I hope this may help. For me, looks like your coin is convincingly a little overweight. Ask someone with an XRF analyzer to help you figure out the actual composition of your coin.
Kennedy half dollar
1947 to 1964
Weight: 12.500 grams
Tolerance: 0.259 grams
Diameter: 30.61
Composition: 900 Ag, 100 Cu
1965 to 1970
Weight: 11.500 grams
Tolerance: 0.400 grams
Diameter: 30.61
Composition: 40% silver clad
1971 to date (excluding the Bicentennial 40% silver clad)
Weight: 11.340 grams
Tolerance: 0.454 grams
Diameter: 30.61
Composition: 75 Cu, 25 Ni on pure CU
1976 (40% silver clad)
Weight: 11.500 grams
Tolerance: 0.400 grams
Diameter: 30.61
Composition: 40% silver clad
Kennedy half dollar
1947 to 1964
Weight: 12.500 grams
Tolerance: 0.259 grams
Diameter: 30.61
Composition: 900 Ag, 100 Cu
1965 to 1970
Weight: 11.500 grams
Tolerance: 0.400 grams
Diameter: 30.61
Composition: 40% silver clad
1971 to date (excluding the Bicentennial 40% silver clad)
Weight: 11.340 grams
Tolerance: 0.454 grams
Diameter: 30.61
Composition: 75 Cu, 25 Ni on pure CU
1976 (40% silver clad)
Weight: 11.500 grams
Tolerance: 0.400 grams
Diameter: 30.61
Composition: 40% silver clad























