There's some basic tricks to using it.
A. Try to build a load where Pmax and Z1 are on top of each other (in the graph), this gives the best groupings
B. Try to build a load with a minimum exit pressure, this will have the least bullet upset.
C. Keep the powder loaded in the brass just under or just over 100% (I use anywhere between 96%-105%), never right on 100%. If it's a 100%, some shells will be compressed and some not, they will have different burn characteristics.
D. After you've modeled a load, shot it and worked with it to get your groups tight, adjust the case volume setting in Quickload to get a matching muzzle velocity.
E. Once you've got a completed load, note the barrel time. This is your barrel harmonic time. Use this to create other loads for that barrel, match your barrel time and you should have a load that groups tightly.
Remember this is a modelling tool, and you must use it in conjunction with results from actual shooting really make it sing.
AB