You can't create an Ackley chamber on a fixed barrel from the parent cartridge chambering, it requires the barrel to be set back which can only be done on a threaded barrel such as a bolt action where the barrel is turned into the action one thread, then the new chamber is cut.
Tim
This is very good information and is true for rimless cartridges such as the 223 Rem. that barenk asked about.
Rimmed cartridges on the other hand are doable in fixed barrel firearms because they can headspace off of the rim. A 30-30 barrel can be done to AI on a Handi-Rifle and factory ammo is no problem. There is also the 22 Hornet to K-Hornet, this is also doable because of the rim to headspace on.
GOOD SHOOTING!
Slufoot