The RML 64-pounder 64 cwt gun is a Rifled, Muzzle Loading (RML) naval, field or fortification artillery gun manufactured in England in the 19th century,[2] which fired a projectile weighing approximately 64 pounds (29 kg).

The calibre of 6.3 in (16 cm) was chosen to enable it to fire remaining stocks of spherical shells originally made for the obsolete 32 pounder guns if necessary.

Mark III guns made after April 1871 were built with toughened mild steel "A" tubes, and earlier Mark III guns were re-tubed with steel and were classified as a siege gun in land service.

Remaining guns with iron tubes were used for sea service.

[4] The gun's standard shell was "common shell", for firing on troops in cover, ships and buildings, weighed 57.4 pounds (26.0 kg) when empty with a bursting charge of 7.1 pounds (3.2 kg).