It all started a month or so ago when I was reloading some .357 Magnum rounds. Out of 300 rounds three of them had no neck tension to the point where I could push them with my finger.
I decided to take a leap and get a Redding dual ring carbide die for it. It’s a spendy bit of kit, but I decided what the hell — if it didn’t work then I’d send it back and blame the brass. Long story short, it worked great. From there I decided to get some more.
Today I got in some more dies — I’ll go over the .44 Magnum dies today!
While it might not look like a big difference, the one on the right is sized a lot less — if you look close you can almost see a step at the neck. The neck size between the two of them is almost the same, but the body is around .006 bigger. This is pretty big (in the big scheme of things). By not sizing the body as much the brass isn’t worked as much — and keep in mind that when you squeeze the brass it has to go somewhere. Without sizing the body as much it doesn’t grow the length as much.
So, this experiment was conducted with a single lot of once-fired brass. All of it was was from a 1000 round purchase a few years back — all of it was Starline.
The key difference is that instead of having one sizing ring like a conventional die:
It has two: one for the body to get that in spec and one for the neck to ensure enough neck tension to keep thing working correctly.
The end result is cartridges that don’t look like Coke bottles. The bottle-shaped cases don’t add anything to the end result, they just work the brass needlessly. Overworked brass gets brittle. Brittle brass cracks.
Now, to the data:
Normal carbide sizer
Dual ring carbide sizer
The last two lines of each table are average and standard deviation. The only odd thing I see is that the standard deviation of the neck size with the conventional sizer is super low. My guess is that since the ring had two passes — one up, and one down — it might iron things out a bit more. There’s no science behind that though, so take it with a grain of salt.
All in all I like these dies. Now I just need one for .40 as well — but they don’t seem to exist at the moment.