Different shotgun activities require different barrel lengths. This article addresses the recommended barrel lengths for various purposes, and the pros and cons of these barrel lengths.
Longer Barrels
Pros: Longer sighting plane, less noise, less muzzle flash, less recoil.
Cons: Harder to maneuver with, heavier weight.
Longer shotgun barrels are generally best suited to hunting and other sporting purposes, such as trap, skeet, and sporting clays. These longer barrels provide a longer sighting plane, which makes it easier to accurately aim the gun. This is because the sights are further apart along the length of the barrel, and it is more apparent when the sights are correctly or incorrectly aligned on the target, compared to a shorter barrel. Longer barrels also produce less noise and muzzle flash. This is because the pressure inside the barrel has dropped to lower levels by the time the projectile(s) exit the barrel. There is also less recoil on a gun with a longer barrel, since the added weight of the barrel reduces recoil. Some people will claim that longer barrels will result in increased muzzle velocity, but this is generally not the case. An 18″ barrel is sufficiently long to allow the gun powder to burn and accelerate the projectile(s) to their top speed, and for the pressure to drop to the point that using a longer barrel doesn’t add velocity to the projectile. In fact, when shooting sabot slugs from a rifled barrel, excessive barrel length (perhaps beyond 30″) could result in additional friction between the projectile and the barrel, reducing muzzle velocity.
The cons of a longer barrel are reduced maneuverability, and added weight. The reduced maneuverability is a prime concern for home defense shotguns, which is why I recommend an 18″ barrel for home defense shotguns. A 30″ barrel would be harder to swing around in close quarters, and would be easier for a home invader to grab the end of. The added weight of a longer barrel can also be a concern for some people, although I feel that the reduction in recoil is generally worth the weight increase.
Shorter Barrels
Pros: More maneuverable, less weight
Cons: Shorter sighting plane, more noise, more muzzle flash, more recoil
Shorter shotgun barrels are best suited to home defense shotguns. The shorter length allows the user to maneuver the shotgun more freely. I recommend an 18″ barrel, which will allow the shotgun to be swung with ease, but will still maintain the full ballistic performance one would expect from a longer barrel.
The cons of shorter barrels are the increases in noise, flash, and recoil. As the projectile exits a shorter shotgun barrel, the (relatively) high pressure gases are released, causing more noise than there would be with a longer barrel. This extra noise can be a nuisance to neighbors, or be seen as a violation of etiquette when trapshooting. Similarly, there is an increase in the muzzle flash, which can also affect the night vision of the shooter or those nearby. Shorter barrels generally weigh less, which means the shotgun will recoil a bit harder than it would with a longer barrel. For these reasons, a longer barrel is generally better for sporting purposes.
Conclusion
Pick the shotgun barrel length that is appropriate for whichever shotgun activity you have in mind. Changing a shotgun barrel is no harder than cleaning the shotgun, and can be done by the user with no tools required. I encourage everyone to buy multiple barrels for their shotgun, and enjoy the use of the proper barrel for each shotgunning discipline.