This cartridge is also known as the .270/245 Holland & Holland Rimless Magnum. There are not many references to it, one being Robert T. Buttweiler’s auction catalog XII-3-352. It was developed by David Lloyd in 1952 (Box date – 15 OA, which translates to 15/08/1952). It is just a 275 H&H Magnum necked down to 6mm (as the headstamp still states “275”). This is possibly a developmental cartridge that lead up to the 244 H&H Magnum in about 1955.

Discovered in the Birmingham Proof House, that recently closed down and sold off all its stock of proof ammo.