Have you ever noticed when you’ve purchased some premium cases, they have a bit of a “rainbow” color around the neck and/or case mouth? It’s not just there for looks, it’s totally there for a reason.
What you’re seeing is an annealed case. Perhaps you’ve read about the technique, or maybe not, but it warrants an explanation.
For years, I’ve enjoyed the consistency and longevity of Norma, Hornady and Lapua brass, and didn’t really know why. I mean, there is the fact that you can pretty much load them straight out of the box, with little or no working. But it dawned upon me when I picked up some once-fired brass from these three companies that they could be reloaded more times than the other cases from the big three manufacturers.
The fact of the matter is that all three companies anneal their cases. The act of annealing brass is a technique which will soften the neck and case mouth, so as to keep the brass soft, and able to be reworked time and time again before becoming so brittle as to split or crack.
So why don’t all cases come with annealed necks and mouths. Well, it’s a process, and the more processes that are involved with any item, the greater the cost. Is it worthwhile? Can we anneal brass that doesn’t come from the factory already annealed? Yes, and yes.
Unlike steel, and pretty well the exact opposite of its properties, brass becomes more malleable when heated and quickly quenched. This technique will ‘temper’ steel (hence the phrase “don’t lose your temper”), but will soften brass.
Once softened, or annealed, the brass will soften where the steel becomes much harder. So, how do we anneal brass that isn’t delivered to us already in that state? Here’s how, but there are caveats, and please heed them.
First, it involves fire, so don’t go getting all Beavis and Butthead on me. Second, it should, under no circumstances, be performed in your home. Like casting your own lead bullets, it is a practice that is best done in the great outdoors, free from distraction and in a place where you won’t start a fire on the scale of Mrs. O’Leary’s fabled bovine arsonist.
You’ll need a cookie sheet, a bit of water and a blowtorch. Yes, Beavis, a blowtorch.
Set your cases upright in the cookie sheet, which should be filled with water almost to the rim. Use the blowtorch to heat the cartridge neck and mouth, or top third, in the case of a straight-walled case, not to the point of melting it, nor to the point where it’s just blackened, but until it’s good and hot, and then use the tip of the blowtorch to knock the case over into the water. The water will quench the brass, and thereby anneal it. You should see that aforementioned rainbow in the area you’ve heated.
There you have it: a rather simple process, yet it takes a bit of responsibility (it’s a blowtorch after all), and your case life should increase two to three fold.
This comes in especially handy when you’ve got cases that are fire formed to an Ackley-Improved chamber, or cases that are so rare that you have no guarantee or being able to obtain them again. Use common sense when using that blowtorch, so I can sleep soundly, please? Happy annealing!