Well, I like to do two ladder tests and see if I get the same results.
Hand weigh the charges so you know 100% what they are.
After you determine the best powder charge(s) (I test best 3 shot and best 5 shot), than make 10 rounds at your max OAL (determined by the max that'll fit in your mag, or the max that you can go before touching the lands) and decrease your OAL in .01" increments.
Shoot two groups of 5 shots of each OAL.
When you find your most accurate OAL, do another ladder test or two with that OAL. Your results will be different than your original if your OAL was originally off alot that what you have now.
Test your results again and see what you can come up with.