When considering purchasing an AR-15, one factor may be the length of the barrel. ArmaLite rifles (ARs) have three common barrel lengths: 16, 18 and 20 inches. Short-barrel rifles (SBRs) start at 14.5 inches and require special paperwork and a stamp tax. We won’t be getting into those here.
When looking at AR barrel lengths, you should first decide what the purpose of your rifle is. In short-range use or home defense, the barrel length isn’t as important. Though maneuverability in close quarters may be a consideration, the short-range velocity isn’t critical. Barrel length becomes more important for target shooting, hunting or all-around emergency use.
The Original: 20-Inch AR-15
The original AR-15/M16 was designed with a 20-inch barrel. This length generates the highest velocity for the 5.56mm. The .223/5.56mm gets its wound potential from velocity. A 3,000 feet per second, 55-grain bullet creates a severe wound. The faster the bullet, the less drop at long range and the less you will have to adjust point of aim for hits to 200 yards. A 16-inch barrel can get you hits up to 150 yards. And a 14.5-inch barrel — an M4 as used by the military — is generally a 100-yard gun. All targets and armor are not equal but for the most part these rules of thumb are correct.
The 20-inch barrel is well suited to hunting for those who take thin-skinned game with the .223. Advantages of the 20-inch include extra velocity and a longer sight radius. And it handles well. Plus, the longer barrel and its attendant full-length gas system make for lighter recoil. Many experienced shooters feel the 20-inch barrel length and full-length gas system are the most reliable. As a range gun or field gun the 20-inch barrel gun is most desirable. Now, if you factor in maneuvering around vehicles or obstacles, the 20-inch barrel is less attractive. And depending on the handguard, the 20-inch barrel is muzzle heavy. That’s great for long-range fire but not necessarily for maneuverability. The rifle is useful for hunting, competition and home defense.
Smaller Barreled ARs
The 18-inch is the least popular AR barrel length, as compromise lengths often are. When the cartridge ignites, the gas rushes down the barrel pushing the bullet. The shorter the gas tube, the quicker gas is picked up, and the more abrupt the action. Short gas tube guns cycle more quickly but generate more recoil energy. The 18-inch barrel is perhaps a good compromise and handles well. Plus, with the stock forward, it isn’t difficult to store. Ruger’s MPR is among the best balances in a factory 18-inch barrel rifle.
The 16-inch (actually 16.5 inches) barrel is the shortest barrel length we may legally own without a host of paperwork. The 16-inch barrel rifle is a carbine type. Coupled with an adjustable buttstock, this AR-type carbine is easy to store and maneuver. As an all-around go-anywhere, do-anything rifle, the 16-inch barrel rifle is surprisingly accurate to 100 yards. It isn’t unusual for a 16-inch barrel AR to place three shots into less than 2 inches from a solid benchrest firing position. And it is easily the superior rifle for fast handling in the home. As for velocity, it isn’t important for defensive use. Defensive loads with the 55-grain soft point or even the 77-grain SMK expand aggressively, usually fragmenting. Handling is good. Practical handling is good to excellent.
Which Barrel Length Is Best?
When you consider the three common barrel lengths of AR-15 — 16, 18 and 20 inches — the easy handling and performance of the 16-inch barrel is the reason the carbine length is by far the most popular. For personal defense and as an all-around recreational rifle, the 16-inch barrel rifle is easily the best choice. The 18-inch barrel is often called the orphan length. I don’t see the advantage in obtaining an 18-inch rifle when the 20-inch barrel length is available. So the 16-inch barrel for most of us, and the 20-inch for those who genuinely need a long-range rifle.
