I have an original Kynoch round and a military actioned Mannlicher-Schoenauer full stocked 1903, British proofed. It says ".256 Gibbs Magnum" on the receiver ring. I use .257 Roberts brass necked to take .264 bullets and shorten the necks to the original rounds length.
Steyr Steve
19-Apr-2015 00:20
The .256 Gibbs Magnum was introduced by Gibbs @1913. It is a 6.5x57 Mauser round with the neck shortened by 2mm. COTW incorrectly links it to the 6.5x55 Swede. The 6.5x55 has a .479" base. The .256 Gibbs Magnum uses the more common"30-06" base of .470". The case length is 2.17". Brass can be made from .257 Roberts, 6mm Remington, 7x57 Mauser, or most of the other x57 cases. Use 6.5x57 or 6.5x55 loading data. The usual caveat applies: Start low and work up carefully and gradually in deference to the older steel in the older rifles.
