If you go down the wildcat path and find yourself with a unique cartridge case that you have to form yourself, there’s a process to follow, and my .22-243 provides a perfect guide.
Although we are talking about a very specific case in this instance, the principles apply to many others.
One of the problems with wildcat cartridges is that there are no standards laid down, particularly about dimensions. As such, each gunsmith has his own ideas.
In my particular case, the gunsmith concerned, who has since died, changed 100 original .243 Winchester cases into the configuration that suited the chamber. In retrospect, I should have asked exactly which version of the .22-243 he’d opted for, or which one it was based on.
The resultant case had a long neck. All I had to do was the load development, a straightforward exercise using 65-grain JLK low-drag projectiles, which was the original idea anyway. From 41.5gn of AR2209 provided the horsepower to drive the projectile at some 3550fps. Three-shot groups were in the half-inch region, and I was a happy rifleman.
Eventually, I needed more cases. That’s when the confusion began.
The maximum trim length as specified by the gunsmith was 2.005” (50.927mm) with a 0.300” (78.62mm) neck length. At first, I thought that perhaps the case was based on a .224 Durham Jet, but this had an overall case length of 2.045” (51.943mm) and a funny shoulder angle (39.36 degrees?).
Next in line was the .22-243 Middlestead, also with an overall length of 2.045” but I thought it reasonable to assume that this case was closest to our example. I did have a forming die that came with the other straight-line dies for the cartridge.
Several statements suggested that the easy way to form the cartridge was to simply lubricate a standard .243 Winchester case and run it through the form die. This worked if you proceeded slowly and reduced the neck in stages. Case length was closely monitored and trimmed to suit the chamber.
However, this is a slow, exacting process if you do not want to destroy the neck. If you go too far, you will eventually start to crush the body of the case.
I fitted a ring to the form and trimmed the die to indicate the maximum length. Next, over two cuts, I reduced the thickness of the neck to 0.009” (0.229mm). The final sizing was to run the formed case into the normal resizing die; they were then checked for fit in the rifle chamber.
All such cases were now ready to be fired.
Many claim it is not necessary to fire-form Ackley. In improved cases, they were originally designed for the parent cartridge to enter the improved chamber. However, I thought it prudent to expand the case again, gradually. The initial case formation was achieved using 25 grains of AR2205 powder topped with polenta and a wad of tissue.
The cases were annealed, both before and after fire-forming. After recovery from fire, the cases were loaded with the standard load of 41.5gn of AR2209 and checked for velocity and grouping.
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