“Any representations by a DA on super hot loads must be started by the coroner. “
Not true. The DA is not restricted to any evidence. the Coroner provides cause fo death and probable method. The DA could just as easily take whatever rounds remain in your gun, your home, your reloading bench, and test them for velocity. However, not a single case of that has ever been documented.
“Must” was too strong a word. Let us say that any representation of super hot loads will be tested against a ballistic gelatin matrix and the results entered into evidence with an opinion stated to the jury.