.375 H&H Magnum

The .375 H&H Magnum also known as .375 Holland & Holland Magnum is a medium-bore rifle cartridge introduced in 1912 by London based gunmaker Holland & Holland. The .375 H&H cartridge featured a belt to ensure the correct headspace, which otherwise might be unreliable, given the narrow shoulder of the cartridge case. Wikipedia
 
Rifling twist1-12 in (305 mm)
Bullet diameter.375 in (9.5 mm)
Case length2.850 in (72.4 mm)
Parent caseUnique
Case capacity95.0 gr H2O (6.16 cm3)
Base diameter.513 in (13.0 mm)
Rim diameter.532 in (13.5 mm)