Best data I could find was, RL-25 assuming 160 gr bullet, for 270 Wby Mag, Pressure test loads (1 ea) 68.2, 69.7, 70.5, 71.1. Accuracy test: 69.5, 69.9, 70.2, 70.6, 70.9, 71.1., I shoot 5 shot groups, recording speed, and MOA.
When starting with an established cartridge I go to Nosler's site and get their load data for the bullet weight I will use and start with the powder that they say yields the most accurate results.
I plug that data, max load, into an Excel spreadsheet I have developed and it calculates the pressure test loads and accuracy loads automatically. The sheet also has a section for listing all the critical load data as well as test results and calculates average speed and SD, once the recorded speeds have been loaded in. I manually input MOA for best 3 shots and all 5 shots, because my shooting ability is usually the biggest variable. After the initial accuracy test I take the most accurate load, with highest speed, and load +/- 0.2 grains on each side in 0.1 grain increments to zero in on the best load. So if most accurate was 70.5 I would load 70.3, .4, .5, .6 & .7 and retest.
If you have Microsoft Excel I can clean up a spreadsheet and send it to you if you like, it may take a couple of days though. It has room for all the relative variables that you need to be able to repeat the load for future use.
Using this method I was able to confirm 1/4 MOA load with only 70 rounds and 2 trips to the range for a factory stock Browning 300 WSM, surprised the heck out of me.