LowBoost, You seem to be a bit scattered. Not good for reloading. Perhaps you are jumping around between too many sources. You do not seem to have a good foundation understanding of reloading principles, but are eager to learn. Focus that to a main reference and work on the basics. Listen to what IDescribe advises, he is spot on for everything. Working up a new load should start with a loading manual that gives well tested and safe data including OAL as tested and max powder charge and bullet used. Start st the low end of powder charge (10% less than max if not listed). Use the listed OAL. This should be safe even with different primer and bullet brand. Work your way up to a max load that does not exceed the max velocity listed. Now you have a baseline for max charge. From there you. Can change one factor at a time and ladder test some more for velocity and accuracy. Increasing OAL will make more room in the case and therefore slightly less pressure so you could test a bit more powder. If you decrease OAL from lusted spec you will increase pressure and sometimes that can be significant. Mistaking OAL reduction for powder reduction is way off the charts of understanding. Really read through a reloading manual and not just skim for tidbits here and there. Reloading is a scientific endeavor, especially when you go beyond tested data. Don't just jump on the latest internet recipe and try to make changes to it without a good understanding of standard principles and methods. Takes time. Better to make simpler well tested recipes that work in all guns to start with. Modify for specific guns only when you truly understand the ramifications of them. Not intending to berate you, just giving you a warning that you are working beyond you level of understanding. We all started at the beginning and had to learn gradually. Take your time and you'll do fine. I've been reloading 30 yrs and made a few mistakes on the way, too! Still learning.