good point....shape of entry hole would also be important. Shot direct to the body would be a round hole...there would be no indication of anything but a round hole....bullet would not be tumbling.
anyway, good luck. the defendant can be garbage, but the issue needs be guilt. low quality types are probably at increased risk of safe and prudent firearm handling. Macho male attitudes encourage unsafe handling.
p.p.s. I think we are assuming a floor of linoleum on top of something quite hard/strong like concrete.
Also, there is the older linoleum that is thicker, harder and stronger than the newer (cheaper) stuff.