Minecraft wiki entry for TNT_cannons, associated text: Step 6. Touch up & check for problems. I purposefully planted a few problems. First, some of the wiring is in the way of the barrel which will severely damage the range. We'll get to that later. More importantly, we need to move one of the repeaters ahead because it isn't providing enough power from where it is. Step 7. Load the magazine. Pay close attention to this part as you will have to do it every time you reload the magazine. Place the TNT into the magazine, from against the side-pushing pistons...