the 6x70R Norma is a new cartridge developt to get roe deer legal energy with the lowest pressure

http://old.municion.org/6Mm/6x70R.htm

its the only cartridge bigger than .22 hornet that is recommended in a barrel insert for a classic drilling.

one of the very few guns actually chambered for this round beside of the inserts https://www.einstecklauf.de/classic.html

mother cartridge was the old pre war 6,5x70R, called pencil cartridge because - well you guess why

http://old.municion.org/Gr/6_5x70R.htm

W.Collath Söhne, 16 ga +9,3x80R, SN 183xx
https://www.egun.de/market/item.php?id=12772365