The go gage on a standard cartridge becomes the no go gage on an Ackley. For this to work, you must set a barrel back to convert a chamber from a standard to an Ackley improved version. The set back is one thread.
It is often easier to chamber a new barrel rather than rechamber the factory to an Ackley configuration. Whether the action is push or controlled round feed, the type of thread, TPI, and timing are all issues that have to be dealt with.
I recently barreled a long action 700 Remington to 6MM Remington. It started life as a '06. My personal preference would be to add two inches to barrel length rather than go Ackley. That said, I have done a few Ackley chambers, and my favorite deer rifle is a 257 Ackley in a '03 Springfield. A VZ24 in 7X57 is a close second. Both wear Pac Nor barrels