Sounds like everything is ticking along just fine. You will find that much OAL variation using premium match hollowpoint like Sierras and Hornadys, so that's a none issue.
Powder charge variation? You'll see as much shot-to-shot variation with every charge being EXACT as you get from .1 grain of increment in a .223. A .5gr change is worth about 40-fps, therefore you can extrapolate a .1gr variation being worth a whopping 8-fps. For reference, my Highpower match load with 69gr Noslers produced a SD of 30-fps last time I checked it, and it will shoot MOA out to 300 yards. If you drop the first-shot outlier it drops to a 10-fps standard deviation, with thrown charges. I refuse to trickle weigh charges, even for 600-yard ammo. And I use extruded powder (Varget and RL-15).
Just keep plugging along and shoot what you got!
