Cross Section Of Different Bullets
Why do the bullets have different gun powder? Some of them it is finer and some more corse.
The grain size and shape effects the burn rate of the powder. The faster the burn, the more impulse it will have. The goal is to have a charge burn for the duration of when the bullet is in the barrel of the gun, so faster burn or not loading enough grains will be inefficient because you aren’t providing enough energy, more like slapping a drag car and expecting it to make the quarter mile. Too much powder charge can be dangerous for chamber pressure and can cause physical failure of the case and firearm, and too long of a burn is just inefficient because you’re burning after the bullet is long gone, like holding the gas pedal to the floor well after your drag car has passed the quarter mile mark and the race is over.