Even if the rocket boost idea won't work, the somewhat simpler notion of a bullet still attached to its case would be bizarre enough for a forensic pathologist to puzzle over.
could the rear of the case be counterweighted with lead to help balance? any space between the bullet and the rear could be filled with zinc or some other light metal too I suppose
Without a "booster" charge would the BATF classify this as AP?
or is that only when using steel or other hard metals?