It's not an Ackley, factory ammo can't be fired in it, brass has to be fire formed first, see handloading for an improved chamber in the FAQs. You can make a true Ackley on a fixed barrel by removing material from the chamber face, then rechambering with an improved reamer and refitting the barrel with a shim, I've done it on a 270 Win barrel, it shoots factory ammo just fine. The chamber face on it wasn't square, so I squared it up by flat filing it, by the time it was true, the chamber was too shallow, so instead of running a standard reamer into it, I rented a 270Win Improved 40º reamer and did it myself by hand.
Tim