I think there are 6 factory derivatives inclusive of the 06 parent round. 25-06, .270 Win, .280 Rem, 30-06, .338-06 A Square, and the .35 Whelen. However, it has been wild catted and converted into propietary rounds in almost every bore imaginable from .224 through .416. JDJ, American Hunting Rifles, Hawk, and several others have made this case the parent round for a line of proprietary cartridges sold exclusively through them. Almost all of them have some sort of Ackley Improved modification to the brass by lengthening the shoulder, changing shoulder angle, rounding the shoulder, to actual Ackley Improved. It is still the grand daddy of the most popular selling rounds in the world. The 30-06 is the most popular selling round in the world, with its fledgling .270 Win being one of the top 5 selling cartridges in the US too. Both added together make this parent round the best selling cartridge ever by a large margin.