This video shows how a men is using a transparent combustion gun to fire an orange through a tube in 20 000 frames per second.
Using a 20 000 fps high speed camera, we are able to tell the difference, between the two types of ignition, one from the back and the other one from the middle,. Although the difference in firing and distance are not that great, we can agree that a spark from the back causes a lot faster ignition inside the transparent combustion gun, making the orange fly out of the tube faster, despite the even expansion of the gasses inside while firing from the middle.
At the end the spreading of the gasses inside the tube are explained, and you can see how they spread, making a pressure around. Would you dare to try something similar at home? If so, always remember – safety first!