Although not specifically mentioned, the charts and graphs illustrated seem to relate to a certain case capacity, bullet weight and diameter and barrel length.
Said another way, a powder type balanced with the cartridge and caliber and bullet weight.
My question is, if we take it to the extremes and use a much lighter bullet, say 100 grains in a .30-06 and use the largest amount of the slowest burning powder that is safe to use, would all the powder burn before the bullet exits the muzzle?
Would it all burn within the first 5 or 6 inches of bullet travel.
It seems to me, to get the most velocity from a given cartridge, you would have to balance the powder burn rate with the bullet weight and case capacity.
The part about the pressure dropping after peak pressure. That is because the bore capacity is increasing as the bullet moves forward.
There is a name for this, but I can't think of it. It goes something like this--you have a sealed container with X amount of gas pressure inside it. You double the size of the container, and the gas pressure drops to 1/2X. If you half the size of the container, the gas pressure increases to 2X. This pressure rise and/or fall is also progressive and at a constant ratio.
That is the reason the gas pressure drops after it peaks in a barrel and the powder is no longer burning and producing gas.
But, as long as the pressure inside the barrel is greater than the pressure outside the barrel, the bullet will continue to accelerate.
That can also be what causes a gun to blow up. If the bullet is not moving forward fast enough to create more bore volume to keep the gas pressure in check, the gas pressure will soon overcome the available volume, pressures will rise, and if they rise high enough, something will let go.
