Ok. Sat and composed my thoughts a bit..
So a chronograph has two coils set up a few inches from the muzzle. They measure the disruption in the field between them.

Because the magnetograph hangs from the muzzle, the coating (gun bluing) may spread the field intentionally created by the designers. Since a copper jacketed round may have a current induced into it. There may be an effect on accuracy. Testing a jlead unjacketed round with this instrument may help to evaluate this.

Call it the particle accelerator effect..

Fodder for for the gunwriters..

Last edited by OldmanoftheSea; 01/14/20.
-OMotS


"If memory serves fails me..."
Quote: ( unnamed) "been prtty deep in the cooler todaay "

Television and radio are most effective when people question little and think even less.