Smooth Bore Firearms are firearms with no rifling (Lands and Grooves) in the bore.
A smoothbore weapon is a firearm or piece of artillery that does not rely on the rifling concept to improve accuracy. Shotguns are the most known examples of weapons that are still smoothbore. Shotguns don’t use rifling since they fire many pellets, making it very hard to rifle all of them effectively. These weapons were designed to kill animals. All firearms were muzzle loaders at first, but it was quickly noticed that adding lands and grooves to the barrel along with a cylindrical projectile made the projectile more accurate and increased the range and trajectory path of the projectile when compared to more spherical projectiles, so rifling was developed.
The most common example is the shotgun, which may be single or double-barrelled. The normal barrel length is between 18 and 36″. However in homicidal shotgun wounds, the weapon will often have had the barrel shortened or sawn-off, usually to < 25 cm or 10″ as a weapon with a shortened barrel is easier to conceal. However, altering the length of the barrel can have a marked effect on the efficacy and efficiency of the weapon as it can decrease the missile velocity by about 20% and the shot may spread earlier. This can have the effect of increasing the diameter of pellet spread on the skin surface to double that expected for the range of fire.
The effective range for a shotgun is approximately 50m. This range can be improved if the end of the barrel is narrowed to keep the shot together for a greater distance, this is termed choking. Shotgun weapons can be fired two or three times faster than rifled weapons but are less accurate than rifled weapons.
In a shotgun there are single or multiple missiles or pellets, fired from the same shell. At close range, these wounds are similar to a high-velocity type of wound. The wounds produced by gunshot injuries can be nonpenetrating, contusions and abrasions, equivalent to a blast injury, penetrating, with an entry and no exit, or perforating with an entry and an exit.
Smooth bore firearms are classified as follows:
SBBL (Single Barrel Breech Loader Firearm) – A single barreled firearm with ammunition loaded from the breech end.
DBBL (Double Barrel Breech Loader) – A firearm with two barrels (stacked vertically or horizontally) that load ammunition from the breech end.
SBML (Single Barrel Muzzle Loader) – Although the firearm has just one barrel, the ammunition is loaded from the muzzle end.
The DBML (Double Barrel Muzzle Loader) is a rifle with two barrels that load ammunition from the muzzle end.