I may have missed something. What exactly is a Coke Bottle 9mm sizing die? Or a Coke Bottle case.
“Coke Bottle” or “Wasp Waisted” cases refers to the shape and appearance the handgun cases after they have been sized with a die that contains a single carbide ring. It is the carbide ring that performs the actual sizing of the case. With only a single sizing ring in the sizing die body that ring can only be designed and manufactured at 1 diameter and that diameter will be the size that performs the primary size reduction required to give the case the neck gripping dimension.
Unfortunately because there is only a single sizing ring the whole case length (except for the solid case head) gets reduced to neck diameter. Now when a bullet is seated the case neck is stretched larger by about 2 thou. (0.002”). So now the finished cartridge has an odd look with the case neck swollen larger by bullet insertion, below the neck the body of the cases is at the reduced neck size and the solid case head is of course at the factory made size.
So with the center of the case body at this reduced size the finished cartridge looks wasp waisted or like a classic Coca Cola bottle.
The only advantage the single carbide ring sizing dies provide is to allow for skipping the case lubing step in the reloading process.
Skipping the lubing step is only an advantage to reloaders using automatic reloading machines that can manufacture several hundred cartridges per hour.
By skipping the lube, the process is speeded up in these machines. The carbide ring sizing dies was made for use in the reloading machines but anyone can use this type of sizing die in their single stage press. But those users will get funny looking ammo.
The down side disadvantage of the single ring carbide sizing dies is reduced case life from over working the case brass.
Now the reloader will be seeing case body splits as well as the usual cases mouth splits.
With annealing the whole case batch at first detection of a case split (any where) will likely salvage the rest of that case batch.
9x19 cartridge case are tapered cases, it’s the taper that make this cartridge unsuitable to be sized with a single ring carbide die.
I do use some Redding Dual Ring carbide sizing dies in 38 Spl. & 357 mag and 45 Colt but all these cases are straight wall cases so the dual ring sizing die works just as well as the old style solid steel sizer.
I still apply lube when using the dual ring dies because the Redding instructions say to lube for increased ease of sizing and less wear on brass and die.
Knowing now about single and dual ring and solid steel sizer dies my preference now is to buy solid steel, there best. Next is the dual ring.
Never again will I use first die set I purchased, a Lyman set with single ring sizer for 38 Spl/357mag.
It worked but it made funny looking ammo.
