Coniston Water per hour () in "Blue Bird K4". Between 1956 and 1959 Sir Malcolm's son Donald Campbell set four successive records on the lake in "Bluebird K7", a hydroplane. In 1966 Donald Campbell decided that he needed to exceed 300 miles per hour (483 km/h) in order to retain the record. On 4 January 1967, he achieved a top speed of over 320 miles per hour () in "Bluebird K7" on the return leg of a record-breaking attempt. He then lost control of "Bluebird", which somersaulted and crashed, sinking rapidly. Campbell was killed instantly on impact when decapitated by the K7's
.300 H&H Magnum the cartridge, this indicates that the cartridges are dimensionally interchangeable. However, as the .30 Super is rated for a lower pressure, the .300 H&H Magnum cartridge should not be fired in a .30 Super. However, the .30 Super can be discharged in a .300 H&H Magnum rifle. As most significant difference between the cartridges was that the .30 Super was loaded to a far lower pressure than the .300 H&H Magnum. The .30 Super drove a bullet at while the .300 H&H Magnum was loaded with the same bullet at . The .300 Holland & Holland Magnum by Chuck Hawks