You should be able to get the specs by searching the web for your brand and specific round. I'm clueless as to how much setback becomes a problem. Do you have a tool to accurately measure the length of the rounds? It might be cheaper to buy one than replacing all your ammo.
"A little learning is a dang'rous thing; Drink deep, or taste not the Pierian spring: There shallow draughts intoxicate the brain, And drinking largely sobers us again."