This helps to explain blow back and also how powder burns occur. The bottle is the best example of blow back because you see the cavity be created as the bullet passes through and then the water rush back in to fill the void which causes water to be expelled through the entrance wound. Also the apple shows how the exit wound will be greater than the entrance wound due to the mushrooming of the bullet as it passes through the apple.
AN INFORMATION CENTER IN FORENSIC SCIENCE, LAW AND PUBLIC POLICY FOR LAWYERS, FORENSIC SCIENTISTS, EDUCATORS, AND PUBLIC OFFICIALS -CASE STUDIES/EVIDENCE
DON'T WATCH WITH THE SOUND ON! The scene with the AK-47 shows the full action of the hammer striking the shell and the slide recoil which ejects the shell. You can also see the bullets twisting in air showing the purpose of the rifling in the barrel.