I understand what you are saying but the law as written doesn't say anything about the caliber of the bullet. It says .243, .308. .30-06, .300, and 30/30. I understand the intent but I also think you could create a wildcat using the .30-06 necked down to shoot a .257 bullet and could be legal. It would have to play out in court but a good lawyer would get you out of trouble.