I am a bit lazy when I reload for accuracy in .223 Remington for my Savage 12. Lazy as far as varying powder charges. My charge is the mid-point for either Varget (25.9) or H4895 (25.0) for 52 gr HPBT Matchking according to Sierra Edition V. Both powders deliver the same performance on a paper target with other variables equal.
Controlling correct case length, seating, headspace, neck sizing with the Lee collet die, flashhole uniformity, and brass annealing are the factors that have had a positive effect on improving accuracy. More so than varying the amount of powder.