"Buerste" fired this volley in news:hssckq$enn$ firstname.lastname@example.org:
Then cavity resonance might not be the best way to measure it, although it's a good idea if you were working with factory-new brass. Either weight or mass are the _only_ ways you'll tell if the load is correct. Also, you'll have to do the final check before you place and swage the bullet.
It _could_ be reasonable that the same station that did the powder loading could measure the mass before and after powder loading, but before the turret turned. The way progressive loaders work, I think it might be better to make a transducer that impinged on the side of the case being measured, than to have a transducer per station, with the requisite problems of connecting them electrically as the turret moved.
There are a number of problems to solve -- elasticity of the clamp that holds the casing, moving the transducer probe to the casing, a calibration method that "knows" how loads within the acceptable range affect the resonant frequency (dropping it, of course), and so on.