View Full Version : cannon balls, why iron?

July 18, 2010, 09:19 PM
why did they make cannon balls from iron instead of lead?

July 18, 2010, 09:46 PM
Probably because cannon balls were used to penetrate walls of fortresses or the sides of armored ships. The hardness of iron means they don't flatten out like a lead ball would.

Antipersonnel ammo for cannons was usually grapeshot or canister shot. This effectively turned the cannons into big shotguns. Also, gunpowder filled explosive shells with time delay fuses were fired from cannons. This is what Francis Scott Key referred to when he wrote "and bombs bursting in air". In 1812, bombs were shot from cannons, not dropped by airplanes.

July 18, 2010, 09:51 PM
Remember the Cannon ball was just a little smaller than the bore.

The first cannon balls were made from stone. Lead wasn't used for cannon balls for several reasons. Some being that it would have been too valuable since the lead was needed for musket balls. Also the heat generated by the gunpowder charge would have melted some of the lead.

Iron could be cast into a perfect shape along with modifications such as filled with gunpowder and a fuse.

July 18, 2010, 09:54 PM
Lower density could mean longer range as well, stronger walls could probably protect explosives inside. Iron would make sense but until now I never considered what cannon balls were made from. I hope to have a small cannon someday but the mortars look like fun, especially the brass ones.

July 18, 2010, 11:26 PM
1. Cheap
2. Armor Piercing
3. Light enough for a person to move reasonably easily

July 19, 2010, 03:48 AM
There was an interesting tv program about our war with Mexico in the 1800s. They were doing detailed examination of the battle scene .To their surprize they found the Mexicans had used COPPER cannon balls !! The Spanish had gone into Mexico for the silver. Copper was a then unwanted byproduct of silver so they used it for cannon balls ! Perhaps they also didn't have a supply of iron ore.

Doc Hoy
July 19, 2010, 06:46 AM
A lead ball would be about half again as heavy as an iron ball. This would mean heavier guns to withstand the additional stress. There are already plenty of accounts of the gun explosions meaning that the science of artillery design and material knowledge had advanced only far enough to result in relatively few options to deal with the higher breach pressures of heavier projectiles. With only limited ability to consistently predict breach pressure and the ability of the gun to handle it, the single defence against accidents was a large safety margin. Hence a heavier gun for a heavier projectile and powder charge.

Heavier guns are:

1. more expensive to make. (Iron was scarse)
2. harder to wrestle around on the battlefield. (Note that the heavier guns used at sea...24 and 32 pounders, which also employed iron shot almost exclusively, were much more massive than those used in the field.)

July 19, 2010, 01:50 PM
Somehow hollering,
"Get the iron out!"
at a slowpoke,
just doesn't have the same effect as
"Get the lead out!"

July 19, 2010, 02:07 PM
depleted uranium wasn't available. rofl.

Doc Hoy
July 19, 2010, 02:42 PM
Sounds like somebody did some work with CIWS.

July 19, 2010, 03:30 PM
Sounds like somebody did some work with CIWS.

If he didn't, I know that I carried at least my fair share of ammo boxes from the flight deck to the 01 level! Those suckers were heavy and big. The ladder and catwalk were narrow and crowded.

It was GM payback for having to help us hump torpedoes, I think.

July 19, 2010, 04:05 PM
I think JohnKSa nailed it.

I hope to have a small cannon someday I have a little, brass Mountain Howitzer that I'm currently building a naval carriage for. Seeing how it's only about a .30 caliber unit, I plan to shoot #0 lead buckshot.

July 19, 2010, 05:08 PM
I read that early cannon balls were made from stone.

While a lead projectile would be heavier for the same diameter and carry further, that would not be an advantage for Civil War and earlier cannon.

Civil War cannon have sights, many earlier ones don't. A civil war Napoleon could hit a pickup truck at 500 yards, and that was about it. Cast iron cannon balls could hit as far as you could see and that was the limit of the accuracy of the things.

July 19, 2010, 05:08 PM
"The hardness of iron means they don't flatten out like a lead ball would."

The Castillo De San Marcos, here in Saint Augustine, Florida underwent a few sieges during its time - and it is made out of coquina stone. When it was hit by the iron cannonballs, they would often bounce off the walls, or indeed, flatten out as the stone absorbed the hits.

July 19, 2010, 05:48 PM
Iron isn't all that hard, but hard enough that it would deform considerably less than lead.

July 19, 2010, 07:37 PM
Cast iron shatters, providing shrapnel. Cast iron can be cast hollow for explosives. Cast iron balls were sometimes roasted red hot before firing to "encourage" enemy ships to catch fire. Lighter and easier to transport than lead, and logistics is a killer in the days of horse drawn supply lines.

Bill DeShivs
July 19, 2010, 08:20 PM
Do you have any documented evidence of pickup trucks being hit with cannon fire during the civil war?

Dropping a red hot cannon ball on top of a load of black powder seems just a little dangerous. Where on the ship did they heat those cannon balls, the engine room?

July 19, 2010, 08:41 PM
If it's true, they probably used some wadding between the powder and the ball. Also, they almost never just poured loose power down the bores of cannons like is often done with small arms.
Usually, pre-measured bags of powder were inserted down the bore. A vent pick was then poked down the vent to make a hole in the bag so the fuse or priming charge could light the powder.

July 19, 2010, 08:56 PM
That was in the days of the tall ships, not steam. :) I have no idea where they heated them, I would have to assume in some variant of a brass monkey. I also am assuming they used a wadding, but once again, relating what I have read and been told, never treid it myself. :D

July 19, 2010, 10:29 PM
The red hot cannonballs would usually have a barrier between them and the powder, yes. I believe they were also handled with tongs. There's a small structure at the Castillo ( yes, my town of Saint Augustine, FL, again ) called the Hot Shot Furnace where the cannonballs could be heated up before firing them off at wooden vessels. I don't know what the shipboard method would be - maybe something similar. The only problem with the one at the Castillo is that the furnace wasn't in place by the US Army until 1845 - and the Civil War brought about the ironclads, rendering it useless ( unless the objective was to give all the men aboard them some horrible concussion injuries ).

July 19, 2010, 11:26 PM
Many sailing ships of the day had a shot furnace on board - the USS Constitution did. It could heat cannonballs, but the real deal was red-hot shot. The idea was that the shot would lodge in the wood of the ship and catch fire. And if it didn't catch fire, it would at least smolder enough to require crew members to attend to it, taking valuable hands away from the fighting effort.

The cannon teams had to work fast, as you might imagine. A powder charge was loaded behind a wet wad, then the shot was poured in. The cannon had to be fired fairly quickly, lest the shot burn through the wad and ignite the powder. Same deal for a cannonball.

Back in the late 80's, when we were privileged to be moored astern of the USS Constitution, I chatted with a few of the crew and we talked about that. They said that even with red-hot shot, it was pretty difficult to set a sailing ship ablaze, unless some particularly vulnerable spot was hit. The timbers tended to be massive enough to withstand fire and crews were pretty well accomplished at firefighting (for obvious reasons). But a burning cannonball or a bunch of smoking shot rolling around underfoot would certainly make things lively - and could always find that "lucky" spot, like a powder charge or a ladderwell down to something more flammable.

I know that whenever I thought that serving on an aluminum ship was hazardous, I'd look across the pier to the wooden minesweepers and figure that life was good.

July 19, 2010, 11:32 PM
Aside from everything else that's been said so far, I wonder if lead cannonballs would be soft enough to deform enough from stacking, transporting, and handling to cause problems.

July 20, 2010, 10:28 AM
Hot shot furnance for the water side cannons at Fort Niagara NY.


Water/entrance side cannons
Land side Embrasures

July 20, 2010, 10:47 AM
Beautiful, thank you for the pictures.

Doc Hoy
July 20, 2010, 02:07 PM
Yup! Quite tubular!