A smoothbore muzzle loader has no rifling in the bore. Smoothbore muzzle loaders were the first design for a shoulder fired weapon. The technology at the time had no way to create rifling on the inside of the barrel. When the round is fired, the round ball would travel down the barrel. Due to the loose fit of the ball round, the ball would bounce off the side of the barrel and exit in a random trajectory. The reason that the 1800th century military units stood shoulder to shoulder in big bunches of men was that the accuracy of a smoothbore muzzle loader was about 75 yards. The rounds had a tendency to fly off in random directions once fired. The only sure fire way to achieve any chance of hitting someone was to fire a lot of rounds in their direction. You can equate this to a snowball fight. There are a lot of snow balls flying about but very little hits.
Rifling is created by several different methods, but the basic concept is that cuts are made in the interior of the barrel to create the lands and grooves of the rifling. The lands will engage the lead skirt of the Minie ball round, the patch of a ball round, or the plastic of the sabot round and impart a spinning motion to the round as it travels down the barrel. Rifling started to become commonplace in the 1900th century. Once rifling was introduced, accuracy increased and the days of the mass military formation ended.
A muzzle loading shotgun is usually a larger gauge muzzle loader that uses either flint or percussion cap to fire. The basic concept of muzzle loading applies, but there are a few extra steps to ensure safety and accuracy. Once the powder is poured down the barrel, an ‘over the powder’ wad is rammed down on top of the black powder. This is to prevent the powder from mixing with the shotgun pellets loaded next and to cushion the shot. The shot charge is loaded next, this is the pellets that leave the barrel and strike the target. A second wad is then rammed on top to prevent the pellets from running down the barrel if the muzzle is depressed. If you enjoy hunting fowl or small game, the muzzle loading shotgun is enjoyable and challenging to use.
WHAT GOES DOWN THE BARREL?
We have discussed how the round gets fired by the three different types of ignition systems. But what kind of round or bullet do you use and what causes the round to leave the barrel.
The barrel will contain a powder charge measured by volume and not by weight. This charge is poured down the barrel or if it is a pelletized form, dropped down. Once the charge is ‘thrown’, the hunter will ram a projectile down the barrel on top of the powder charge. It is very important that the round is fully seated against the powder.
When the weapon fires, the powder turns into a gas and any space between the round and the powder will lessen the gas expansion and reduce muzzle velocity. There is a touch hole or some way for a spark to enter the breech and detonate the powder charge in the barrel. Once this detonation occurs, the round will exit the muzzle.
The easiest way to imagine the powder charge and round in the barrel is to think of the barrel as a modern casing that is holding the powder and shot. There are 3 types of rounds a muzzle loader can fire.
The round ball is spherical in shape. It has very little surface area to engage the rifles lands and groves to induce rotation. These rounds are usually wrapped in a cloth patch that will engage the rifling and cause the round to spin once it has left the muzzle. Round ball is the traditional projectile used. In a smoothbore weapon, it is the only thing to use since there is no rifling in the barrel to engage. You can use other types of rounds; it just is fruitless since there is no rifling to engage.
A conical round or Minie ball looks like a small rocket, squared at the base and pointed at the end. The base is hollowed out to allow for a thin ‘skirt’ of lead to be expanded under pressure from the burning black powder. This skirt engages the rifling and creates a better seal for more consistent velocity. This type of round was used extensively in the U.S. Civil war and the Crimean war and created devastating wounds. Using this round eliminates having a patch since the round skirt will expand outwards and will engage the rifling. This decreases reloading times.