Civil War Artillery Ammunition
Solid Shot
Cast-iron solid shot is the familiar spherical ball for smoothbore cannon. For rifled cannon, the elongated projectile is called a “bolt.” Both were useful for attacking fortifications. The technically advanced rifled bolt made masonry fortifications obsolete, as demonstrated by the walls of Fort Pulaski.
Shell
Shell, as its name implies, is a hollow iron projectile filled with a bursting charge of black powder. All spherical shells and some rifled shells used a time fuse to ignite the charge. Rifled shells could also use contact fuses.
Case Shot
Also called shrapnel, case shot improved on the simple shell by adding small lead or iron balls to the interior of a thinner-walled projectile. They exploded in the air using time fuses.
Canister
Canister is simply a tinned-iron can full of iron or lead balls packed in sawdust. The effect is like a giant shotgun blast, producing thick yellow clouds of dust that coat the enemy. Canister is short-range anti-personnel ammunition.
Grape Shot
Grape shot, similar to canister, has fewer and larger balls held together with iron rings or trussed up with fabric and twine (quilted grape shot). Normally naval ammunition, grape shot was occasionally issued to field artillery.
Each model of cannon had a Table of Fire affixed to the inside lid of the limber chest showing the elevation, range, and time of flight for each kind of projectile.
When the gunner determined the range of the target, the men at the limber chest would give him the elevation, in degrees, for aiming the piece, and the time of flight to set the fuses. Experienced skill was needed to extrapolate the ranges given in the table.
The limber chest was usually the same size for all field pieces. The amount of ammunition it could hold varied with the caliber and rifling. Each chest included some of each type of ammunition used by the piece.
Fuses
Solid shot, canister, and grape all operate on the same principle as musket fire; the projectiles are simply flung at the enemy by exploding a large charge of powder behind them. However, shell and case shot are designed to explode at or near the target using a fuse (spelled “fuze” at the time). There were two basic types: time fuses, which burn slowly enough to ignite the main charge of the projectile after a predictable number of seconds; and contact (percussion) fuses, which explode on impact.
Time Fuses
The oldest and simplest form of time fuse was a cylinder of wood tapering almost to a point and packed with a composition of grainy powder moistened with whisky or alcohol. The rate of burning would be determined by testing every lot produced and marking each fuse in increments of one tenth of an inch. The needed fuse was cut to the right length to burn the desired time.
The paper fuse was more reliable because it could be made with more even density. They were cut to length and inserted into a wooden fuse plug in the hole of the shell. Paper fuses were color-coded: yellow burned 5 seconds to the inch, green 7, and blue 10. Confederate fuses were produced at multiple ordnance locations and were less predictable than the Union fuses, all made in one location.
Both wooden and paper fuses suffered from the shocks of field use that broke up the uniform composition, contributing to unpredictable gun performance.
These simpler time fuses were replaced by foreign waterproof fuses that burned at a known rate. The most successful of these was the simple Bormann fuse. Within a squat threaded cylinder of metal was a groove running around the circumference. A channel at one end of the groove led to the center of the fuse, which was in turn perforated to communicate with the charge inside the shell. The top of the fuse was sealed with a thin sheet of tin, graduated in seconds. The cannoneer at the limber chest would screw the fuse into the shell and punch a hole in the fuse at the desired number of seconds. Their expense and time of manufacture made the continued use of paper and even wooden fuses necessary.
All time fuses were ignited by the main charge behind the projectile.
Percussion Fuses
Percussion fuses explode on impact. They generally employ some sort of spring or slider mechanism to arm the ammunition by inertia, throwing a plunger to the rear upon firing, then allowing it to fall against a percussion cap upon striking. Complex, often delicate construction made them unsuitable for regular field use because they could become armed during transportation and loading.
The worst horrors on the Civil War battlefield were produced by artillery fire, and the greatest of these was canister at close range.