To be honest, sjones, I believe what you are doing wrong is worrying about it too much.
For the .45 ACP you do want a little lip outside the case, but the exact amount depends more on how well the round chambers in your gun. The OAL will probably be different for different SWC bullets, even for the same weight. Some have longer noses than others. The main thing is to get enough of the bullet in the case so that it is held tightly but not too far in such that it raises pressure too much.
If 1.250 OAL works well in your gun/magazine, then standardize on it for that particular bullet and just go shoot them.