1967 Centennial Coins

So do the 1968 .500 silver quarters weigh 5.83 or 5.05? If all the silver quarters are 5.83 g, there should still be a difference in volume. I figure the .500s would contain 0.325cc Cu and .278 cc Ag, or 0.603 cc total, and the .800s would have .130cc Cu and .445cc Ag for a total of .575 (assuming 8.96g/cc for Cu and 10.49 for Ag). By that logic the .500s would have about 5% more volume than the .800s, probably difficult to measure accurately enough. The conductivity of the coins would probably be easier to measure, but silver is only about 6% more conductive than copper so the difference between the mixes would be small, and maybe surface corrosion would throw off the measurement.