I can easily be corrected on this, but I believe MOST of the explosive power needs/does take place in the barrel and not the cylinder. That is a well-known warning to most experienced hand-loaders and in particular some rifle cartridges. You want just enough powder burned to start things moving inside the cylinder bore. If you down-load a round too far, all the powder ignites within the cylinder, which is not a good thing. I can understand how what is stated above can happen.