Hey jaw3, here's the calculator I use. It's real simple to play around with. http://www.handloads.com/calc/

Based on your statements about the velocities you are getting with those two bullets I assume you have access to a chronograph (unless you're going by book figures). I've used my chrono to track velocity increases as I increased loads in 5 or 10 grain increments and it's fairly easy to identify the point where the velocity stops increasing even though you increased the charge. When that happens you've found the maximum "usable" charge. Most of the time I find the most accurate loadsomewhere below the maximum usablecharge - but not always. Sometimes the maxusable load is themost accurate one.

On at least one occasion I had accuracy stay about the same over a wide spread of charges (95, 100, 105, 110 and 115 grains of powder), but velocity increased only between 95 & 100 and 100 & 105 grains of powder,then started decreasing at 110 and 115 (even though accuracy stayed about the same).