A lot of you might or might not know that many calibers were developed using cases that were already available. One of those being the 243 Winchester whose parent case is the 308. Since 308 is a NATO case (7.62x51) there is a ton of it out there and it is usually had pretty cheap especially in quantities. Since 243 brass is less common it demands more money. Because of this People like me re-form the more common cases into ones that they need.
Here is a short outline on how to get started in doing it yourself. There are other ways of doing it but this is how I have done it and it works for me. One thing I will note is that when reforming cases (especially military cases) is that the internal volume can be less due to the thickness of the walls and webbing. It is highly recommended you re work up your loads
OK... Lets begin!
I use a standard 243 die. that has been wiped clean of lube residue. Too much lube is is your enemy because it builds up in inside the die and has nowhere to go other then pushing divots in your cases and crushing necks. Ive found that imperial lube works the best because it can go on very thin and is super slick. Lube the entire case
Here is a picture of the die in the press. Note that the de-capping pin had been removed
Here is a case getting formed. Take your time and lots of little strokes are your friend. If you go too fast you will just ruin the case.
After the case is formed in the video you might notice a line in the case neck that looks like a crease. It's not. It's the old step neck that was pushed back in forming.
Some calibers like the ones that get necked up in size might need to be fire formed. This is simply the process of firing the case in your gun so it can match the chamber.
Now, You could load up the cases you have just made but for the most part they might not last as long as non re-formed cases because they have probably been work hardened from being shot and the re-forming process. I anneal the necks to soften them up and make them last longer. Only anneal the necks or you will / could have case head separation and that is bad! Again, there are lots of ways to do this but this is what works for me.
I put them in a tray ( or bowl in this case) of water that goes up as high as I would want to anneal them. the water keeps the base from getting too hot. Then i torch the necks all around for a second or two until there is just the faintest of glow. and knock them into the water.
For those of you who wonder why I don't soften the necks prior to forming and making the process easier here is why.
The neck is too soft to support itself during the re-forming and collapses.
Well that's about it.