Annealing brass is pretty simple. Annealing, which involves heating the brass to about 800 degrees, softens the brass which makes it suitable for point forming & softer so that it will be appropriately engraved by the rifling.
Annealing for swaging is different than annealing for reloading in that for swaging, we want the entire piece of brass to get to a uniform temperature. Annealing for reloading entails heating only the case neck, while keeping the area bow the shoulder (particularly the web) unaffected. This is critical so that the part of the brass that withstands the pressure of the cartridge load stays hard & strong.
Per the guidance of my die maker, annealing should be done after derimming. Presumably, annealing before derimming will cause the derimming punch to break through the brass more often. Annealing does need to be done before point forming, however. If the brass is too hard when the point is formed, it will fold over & crease, causing a defect.
Some that anneal for swaging use a Lee casting pot dedicated to the task. Testing has found that these casting pots heat to the right level. In my case, I’m using a propane burner and a flat toaster oven tray for annealing. I’m covering the tray with aluminum foil and laying out one layer of brass. Then, I’m covering the brass & tray with another layer of foil with some space for air. I poke a thermometer through the top layer of the foil to monitor temperature. Alternatively, I’ve also used a clean pot on the propane burner; others anneal in a BBQ. The method of heating the brass isn’t terribly important, so long as they get hot enough, long enough.
Using my method, I’m finding that it typically takes about 20 minutes to heat to 800 degrees. It is important that all of the brass be heated, and it can be difficult to make sure they’re all heated evenly. So, I leave the heat on a little longer, open the foil to move & stir and move the pan around over the heat. When I’m confident that they’ve all been annealed, I dump the brass in cold water. This isn’t necessary to assist in the annealing process; it simply makes the brass able to be handled quicker.
A way to check .22LR brass for proper anneal is to pinch the mouth closed. Unannealed brass can’t be pinched closed; annealed brass can be pinched closed with relative ease.
One the brass is annealed, it must be cleaned again. I wet tumble, using the stainless steel pin method outline on another page. Be sure to ensure that the brass is completely cleaned of any scale or stains that result from the annealing process.
Clearly, there are many ways that brass can be annealed for swaging. So long as it gets hot enough, and all of the brass is annealed, none are ‘wrong’. But, efficiency is important – find a method that doesn’t require you to use a propane torch to heat each piece of brass individually and you’ll be happier.