If you had a rear locking action and had a sulphur cast made of the chamber and had custom dies made for it, Would it still have problems with it still stretching brass ? in a hunting rifle? its probably no big deal, as it only gets shot at game, but if its used alot for both target shooting and game, etc, then maybe the cost of brass becomes a consideration if its something like a 7 x 61 S and H .Thanks

your pretty vague?
What caliber and rifle?
Yes to th die and stretching.
If you fire form and then only neck size you should not see a problem with the brass

You mean stretching as in Steyr-Mannlicher, Schultz&Larsen and Remington 788? In a word "NO".

The answer is yes absolutely.
The stretching is due to the long length of the bolt and receiver under load.

You can neck size ammo for these actions and it will still stretch and separate.
The same thing happens with with rear locking lever guns operated at high pressure, like the Savage 99.