Ever wonder why a primer is at the rear of a cartridge and not the center? Would it not make more sense to have the ignition in the middle of the case to get a better powder burn? At face value the questions seem like a logical hypothesis.
Testing the question is Dustin with Smarter Every Day, a fantastic YouTube channel that utilizes graphics, slow-motion video capture and graphics to break down often complex phenomena like how cats always land on their feet and burning astronaut pee. Or interesting topics like being strapped into a powerless helicopter and how to escape from a car window.
Using a clear potato gun (which was used to demolish a watermelon to spectacular slow-mo effect), Destin tests two permutations of ignition, at the rear of the cannon and in the middle. Surprising to me, the ignition in the middle is actually the less efficient of the two methods due to the fuel consuming oxygen prior to reaching the edges of the combustion chamber.
By his experiment, the rear-igniting cartridge is actually the most efficient capture of energy as the oxygen needed for the explosion is consumed at a steady rate, not outpacing the rate of combustion.
Enjoy the video below, and you will at least be smarter today.