The reason I said entering case length and COAL is to determine seating depth which affects the loaded starting volume of the cartridge. Granted with some bullets, especially with irregular meplats like some hollow points, the seating depth and volume may vary. I actually use a comparator (set for the lands) for this but use the derived COAL for the data field in QL.
The case volume of the fired case shows the expanded volume of the case which helps determine the pressures generated. This will be determined by the weapon chamber because the case will expand to fill the chamber during firing then contract slightly after firing. This is unique to each weapon. The maximum pressure does not change with barrel length but the final muzzle velocity and the bullet dwell time is dependent on barrel length. Remember, this is an INTERNAL ballistics program.
The other thing that QL does not take into account is ambient temperature. Especially with older powders that are not as temperature stable, the burn rate coefficient can change with temperature., I have seen RL-17 change 5% with temperature variations from 35 degrees F to 75 degrees F in my 6.5 Creedmoor. I try to do load development with testing at ambient temperatures as close as possible to the temperature range I will be doing hunting or competition shooting.
Finally, the QL updates do cover many new powders, but also there are so many new bullets being developed that the updates are useful for this new data.
