I think the total stack in a A2 system has to total a 23 or something. I think the other systems may have different spec but I couldn't tell you for sure. I'm still in the beginning stages of learning basic master keying myself.
If a lock is a puzzle, then its key is the complete picture
Eyes_Only,I printed out some work sheet's from the link that you gave me.It took a few attemps,but think I have it now.A customer come in with 3 ket's that have to work the cores. Good thing we don't stock the Sargent I.C. cores,I gauged his key's,and told him that I will order them,giving me time to learn how to do it. Thanks again