Has anyone ever tried to resize the 338 winchester magnum neck and then fireform the case with cornmeal to blow the shoulder back forward to develop 7mm rem. magnum brass. I know this seems like alot of trouble just wandering if it can be done, or is there an easier way to develop a 7mm remington mag brass??

I form first then fire, there is .005" difference in length between the 338 Winchester and the 7mm Remington mag from the shoulder to the head of the case.

the 338 Winchester is the longer of the two, what does that mean?

The 7mm Remington head spaces on the belt, because I form first I form the case to fit the length of the chamber from the shoulder to the bolt face. Meaning I use the additional .005 to take up the space between the shoulder if the chamber and shoulder of the case, this method/technique allows me to head space off ot the shoulder of the chamber.

I would suggest you attempt necking the 338 down to 7mm first, then, if the case does not chamber start full length sizing the case in increments of .002".

I have forming dies for most of the cases I form, when using the forming die the case behaves in a predictable manner.

F. Guffey

hammer 2506, I have at least 100 7mm Remington mag cases, I need some 338 Winchester mag cases for a few wildcats, if interested let me know if you would be interested in trading.

F. Guffey

There is nothing magic nor arcane about forming 7mm Rem from .338 Win brass. Simply run it through the 7mm FL sizer, with the sizer die positioned in the press only deep enough to allow the sized case to enter the rifle's chamber (this may be fully against the shellholder or something less). Now, measure the case length (which will have grown a bit) and trim if necessary.

The only question is whether the neck walls will be too thick to allow a loaded cartridge to chamber easily. If the loaded cartridge binds in the chamber at the neck, then the resized case neck walls will require either turning or reaming. However, since most factory chambers are rather generous in the neck dimension turning/reaming is usually not needed.