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With selected bullet and primer, load one bullet at SAAMI length, at half grain increments, from lowest to max suggested. So if suggested range is 68.0 to 71.0, I'd load one bullet in each increment at 68.0, 68.5, 69.0, 69.5, 70.0, 70.5 and 71.0.
Shoot ladder test (yes, only one bullet per increment - you had better be on your A game and willing to call shooter error/flyers). Do this until you notice pressure.
If you find 3 consecutive increments that group well, focus on that "node". Alter the charge weight and then seating depth. Hopefully you find a unicorn.
If you don't find a unicorn, move on to the next variation (either swap to different powder or give up on that bullet).
SO, I'm simple concise terms, what's your process?