Can I make 6mm brass out of...

[Catfish]

When necking down 1 case to form another you do increase the neck thickness of the brass. The more you take them down the thicker the necks become. I have never found this to be a problem with any factory chambers but often have had to turn necks for custom chambered rifles. The thick necks also reduces the case capisity slightly and increase the presure nessary to pull the bullet. In other words you may have to reduce the amount of powder you are now useing to keep presure where they are now. I formed some .204 brass from .222 mag. brass befor the .204 brass was avaliable. I really haven`t compaired the accuracy side by side yet, but the fromed brass gives me close to the neck expantion I like in my custom chambers, abt .002. It will also take alot more presure to pull the bullets from the from brass which I personally don`t think matters much as long as the bullet pull is conisitant.