I have been looking for a supply of affordablr brass to make a longer necked version of the 7mm super mag. I currently make the brass out of 357 supermag brass but you end up with a neck about an eighth of an inch long.
An alternative is the expensive 5.56 x 50R brass. I have just noticed a 8mm x 50R French Lebel case which is quite affordable. Is this a similair bras which I would only need to reduce down to 7mm, or is it an entirely different beast?
Peter

The 8mm Lebel has a rim diameter of 0.627, and a diameter of body inside rim of 0.534.