If you want a true ackley improved chamber that you can shoot factory ammo in, go 6mm Ackley, the 243 Ackley will be handload and fireform only, whether it can be done by hand is another matter, the 243 chamber has minimal taper, so it might be a good candidate for hand reaming, I've done a 270 Win to Ackley by hand, it just depends on how careful you are in keeping the reamer from wobbling and making an out of round chamber and how well the reamer pilot fits the bore. I have two 243 Win barrels that I had rechambered to 6mm Ackley by Wayne York, he has the reamer if you want it done by a smith.
Tim
