MythBusters - Leaking Powder Keg

Does a moving barrel leaking gunpowder, leaving a trail, and when lit travels up the trail catching up with the barrel and explode just like in cartoons?

The Mythbusters team got on the case. They called on the expertise of pyro-technician Rob Clarke to recreate the type of thing seen in old films and cartoons with a standard barrel of gunpowder which of course has the usual ACME powder keg.

He starts of course with the prerequisite black powder, sourced from a local gun shop which is the closest thing available to the stuff used in cowboy movies. They start with a powder trail just a couple of feet long just to see what happens. Now, as anyone in the firework industry will tell you, black powder burns really quickly so there is not much chance for the good guys in a cowboy film to run ahead of the trail to kick the barrel clear for a starter which was very soon established as you can see in the film footage it takes a split second to burn the couple of feet laid down.

They decided that they needed to have a more controlled, finer, and more consistent line of powder for the experiment to work so they created a makeshift powder horn to create the 3 foot long fine trail to see what happened next. It took around 4 seconds to burn which was not what they expected and much more in accordance with what they had seen over the years in old westerns. They decided that they needed to make a full attempt so off they went to what they acknowledge as a second home at Alameda Bomb disposal range under the watchful eye of Sgt. J D Nelson.

As the ground round about is very un-even and they wanted to be able to see the powder, they first created a ‘floor’ of around 20 feet in length. The first attempt clearly showed that with the small trail it was more than possible to avert possible disaster by kicking away the line of black powder long before it reached the barrel and exploded.