What they said
What Al said about bumping the shoulder on .222 brass can give you a thicker neck. You could even take it a step further by shortening .223 brass. I use a fixture in the vertical mill for rough trimming the cases to length very quickly. After the first firing, I precision trim.
The other guy mentioned a Lee collet die. They do work very well. I only use a collet die for the 30-30, and it has shot zeros. The only things I would add to the collet die is modifications. You can cut a little off the bottom of the collet with a lathe, and get the collet to size a little further down the neck if you want to. You can also make spacer rings for the bottom of collet dies that adjust the collet length for longer cases. Basically this makes collet dies caliber only specific, not case specific. Another trick is to polish about .001" off of the mandrel if greater neck tension is desired. Having mandrels in various sizes allows you to duplicate bushing dies, which allows many options on neck tension. Put a small amount of grease on the tapered section of the collet for long life and smoother operation.
I have also taken Lee carbide pistol dies and opened up the inside diameter with a diamond grit stone. This makes a ring die for sizing the base of the case that requires no case lube. This can be used in conjunction with a shoulder bumper in the top of the ring die. The shoulder bumper is a floating sleeve that goes in the top of the ring die. The shoulder bump bushing has to support about .1" at the top of the case body, otherwise the shoulder bump will swell the body-shoulder junction diameter, and keep the round from chambering. This method can be applied to any cartridge for lube free sizing, including the 6PPC. The floating bushing can also carry a carbide neck bushing, allowing one step resizing without case lube.
Michael