As always, fire-forming is done by one of two methods. Most of you will fire form the brass with loaded .243 Winchester. Ackley always said to use factory loads, or reload equivalent ammo to have a "snappy" load to form the case out properly. You never want to use a reduced load to form with, since you need the pressure to form properly. If your rifle is chambered properly, you should feel a slight amount of resistance as you close the bolt on a new piece of brass. If you do not get this "feel", you may need to seat the bullets out to .010" to .015" into the lands to make sure that the base of the case stays in solid contact with the bolt face.

The fire-forming method I have been using more lately employs medium burn-rate pistol powders and Cream of Wheat. I will start by loading about 10 grains of SR4756 or Unique into the case, and then I fill the case up to the body shoulder junction with Cream of Wheat. I will then take a large pinch of polyester filler, which can be found at any fabric supply store, or sewing department, such as at Wal-Mart. I will then take the pinch of polyester and load it into the case so that it fills up the shoulder area of the case effectively making sure that the filler is held securely over the powder for fire-forming. During the fire-forming, I like to dry brush with a nylon bore brush every 10 to 15 rounds. This removes any loose debris from filler that has accumulated. [Editors Note: Do NOT seat a bullet using this "Cream of Wheat" method. You can cap the case with a bit of wax to keep everything in place. However, Bob finds the wax is not necessary if the polyester filler is placed securely.]

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I thought the cool thing about the Ackley was you could fire factory ammo in it all day, and just get fire formed brass out of it. Maybe I missed something.

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You are correct and it is essentially method 1 above.  I think the only additional tweak proposed there is to attempt to assure the case head is up against the bolt, to minimize rearward stretch.  This rearward stretch can occur if you have head space pushed out by the ejector pin and/or the firing pin, so when the case grips the chamber walls then stretches to the rear to meet the bolt face during peak chamber pressure, the stretch will occur in the more sensitive area of the case body, the section near the case head.

The most important innovation that Ackley brought to the “improved” concept was with regard to bottleneck rimless cases. He chose the simplest of mechanical solutions to insuring that his improved cases would safely fire factory loads. He shortened the chamber by .004” (4/1000 of an inch). Because the factory case is then a crush fit between the bolt face and the junction of the neck and shoulder, proper headspace is insured. This is why Ackley prescribes setting the barrel back on such cases. You will note that if you follow these simple guidelines there is no confusion about the headspace measurements for “Ackley Improved” designs in rimless or rebated cases.

Some confusion seems to arise out of this headspace issue. Folks get confuse between the set up for a rimless bottleneck case and a rimmed or belted case when discussing ‘Improved” chamberings. Rimless and rebated cases are the case designs which always require a barrel set back to be properly headspaced. As mentioned in the paragraph above headspace on an Ackley Improved rimless or rebated designs is .004” shorter than standard. The shorter headspace means you have no choice but to set the barrel back if you want correct headspace.

There are special Ackley, go-gauges, they have the same shoulder angle as the parent case but they are shorter. This ingenious method effectively controls headspace with factory cartridges in the new larger, ‘Improved’ chamber. The factory cartridge or parent go-gauge becomes the no-go for the new chamber. This system works because the parent go-gauge is .004” longer than the Ackley gauge, exactly the same as the difference between the parent go-gauge and no-go gauge. Example: 30-06 Ackley Improved go-gauge is used with the standard 30-06 go-gauge as the no-go gauge.

The only place the factory case will touch in the new chamber that matters is the bolt face and the junction of the neck and shoulder on the case. It will actually slightly crush the case shoulder when you close the bolt on the factory round. If you eject such a case unfired you will normally see a shiny area on the shoulder where the case was crushed just a little. This crush fit maintains proper headspace during the fire-forming process.

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After you fire form the brass do you have to anneal the cases afterwards?