In 1820, efforts to apply rifling
techniques to the cannon began. 
The Crimean War saw the British 
use of such weapons, but their 
poor performance led them to be 
withdrawn from service.  By 
1857, however, France rekindled
interest in the weapons, using 
rifled cannons on gunboats in
the Baltic.

During the period between 1840 
and 1860, better casting and 
machining techniques led to a 
more perfectly spherical shot.  
Another trend was standardization
of caliber.  The French were 
first to standardize in 1820, 
dropping the 12, 18, 24, and 36 
pounder guns in favor of the 30 
pounder; by 1839 the British had
adopted the 32 pounder as their 
standard gun.  The US followed 
Britain in 1845, adopting the 32
pounder as their standard gun 
size.  This standardization 
greatly simplified the types of 
shot and charge, reducing the 
possibility of error.

The most successful rifled 
cannon of the era was Britain's 
breech-loading Armstrong.  
Designed in 1854, it began 
production in 1855 and was 
followed by the Whitworth and 
the Blakely.  All three were 
purchased and used by the 
Confederacy.

The Parrot gun was the rifled 
cannon most widely used by the 
North during the Civil War.  
While not the best rifled 
cannon of the time, it was easy 
to operate, durable, and 
inexpensive.  The Parrott 
began to reach the Union
navy in 1862 and was well 
received.  There were other 
rifled cannons used by the Union
navy, but by 1864 the Parrott 
was the only one still being 
procured.

During the American Civil War, 
the percentage of rifled cannon 
to smoothbore cannon was smaller 
in the navy than in the army.  
The rifled cannon had a lower 
velocity and therefore penetrated
less armor making the smoothbore
much more effective against 
ironclads.  In addition a 
smoothbore ricochet would 
continue on line to the target 
whereas a rifled ricochet could 
deflect in any direction.

Despite these difficulties, the 
rifled cannon was a step forward
in cannon technology; its only 
drawback was not the rifling, 
but the weakness of the cast-iron
from which it was made.  
Prussia's Friedrich Krupp began
experimenting with steel cannons
in 1851, as it was four times 
stronger than cast iron and 
twice as strong as wrought iron. 
However, it was not until the 
1880's that improved engineering
and slow-burning powder made 
steel a viable material for 
cannon manufacturing.