Whitworth also designed a large rifled breech-loading gun with a 2.75 inches (69.85 mm) bore, a 12 pounds 11 ounces (5.75 kg) projectile and a range of about 6 miles (10 km).
The spirally-grooved projectile was patented in 1855.
This was rejected by the British Army, who preferred the guns from Armstrong, but was used in the American Civil War.

While trying to increase the bursting strength of his gun barrels, Whitworth patented a process called "fluid-compressed steel" for casting steel under pressure and built a new steel works near Manchester.
Some of his castings were shown at the Great Exhibition in Paris ca.
1883.
Whitworth also designed a large rifled breech-loading gun with a 2.75 inches (69.85 mm) bore, a 12 pounds 11 ounces (5.75 kg) projectile and a range of about 6 miles (10 km). The spirally-grooved projectile was patented in 1855. This was rejected by the British Army, who preferred the guns from Armstrong, but was used in the American Civil War.
While trying to increase the bursting strength of his gun barrels, Whitworth patented a process called "fluid-compressed steel" for casting steel under pressure and built a new steel works near Manchester. Some of his castings were shown at the Great Exhibition in Paris ca. 1883.
Joseph Whitworth