.salvo # remains the same, but there is a preset delay after the bomb impacts the earth. I believe that it was ".d05, .d10, .d15," etc. Example: I had been chasing an enemy fighter and when I was approximately D1000 my plane blew up?(!) I was stunned and one of my fellow countryman explained that the enemy fighter had dropped a bomb with a 10 second delayed fuse. After that when I saw a puff of dust under an enemy aircraft I broke hard left or right.
It takes a different skill set to drop a bomb at high speed when flying that low level.