Hopefully this works, not the best picture in the world but this will show the basic steps in the forming process of my 6.5 Gibbs. In the above post I mentioned the o6 as the parent case, but due to necking down and the possibilty of worked hardenind the brass either 270 or 25-06 brass works better. With the 270 win case the neck is actually a few thousandth's longer.