Before you changed the powder property, how do the velocity differentials compare (chrono vs QL) between your two projectiles with the same input parameters kept constant (except for bullet/seating inputs)? Do both bullets have higher chrono velocities compared to QL? or lower? Are they similar in magnitude?
Weight factor and initiation pressure can also be used to fine tune the model.
All 3 bullets that I shoot with this powder are faster over the prochrono than the quickload prediction. I played with it some more and realized that my velocites are 15' from the muzzle. I used my ballistic program to estimate the muzzle velocity, and after adjusting the burn rate to match one of the bullets, that same burn rate predicts very close to what I'm getting for velocity with the other two bullets. This is a very cool program:) I'm using it to try and find loads that match the optimum barrel timing nodes from Chris Longs calculations.
A friend of mine has a very accurate load for his 300WM, in may he shot a 5 shot 4" group at 1050 yds. He just got the quickload program so he entered the specifics from that load and after adjusting the burn rate to match his actual velocities, the barrel timing falls exactly on an optimal node. Could have saved himself some time and component's finding that load if he had the program before;)