In this piece, we’re going to take a pass at addressing the question: what’s the shortest effective barrel length for an AR15? To do so, we’ll start with a little bit of general ballistic science to get some basic concepts under our feet. From there, some specific commentary on the operating mechanism of the AR platform, specifically the gas system, is important.

But first, let’s define effective. Here, we mean an effective barrel length as one that can be used in an AR with which you can reasonably expect to engage human-sized targets out to about 300 yards with some skill involved.

Ballistic Science 101

When a bullet is fired, the burning powder builds pressure behind the bullet, pushing it forward through the barrel, where the bullet roughly seals against the rifling, accelerating as it travels down the barrel.

In general terms, greater barrel length means more velocity, which, in turn, means less bullet drop and greater accuracy. Of course, there’s a limit to this: a six-foot barrel would not net you many gains in velocity, but it would make the rifle extremely unwieldy, something like an old-timey Punt gun, which was a bow-mounted shotgun people used to hunt ducks.

AR15 Gas Systems

Regardless of barrel length, the AR15 is a direct gas impingement gun, requiring a gas tube that runs parallel to this barrel. To have the gun cycle as a semi-automatic firearm rather than a bolt action one, you’ll need to have a function gas system. These days, gas systems come in several more or less standard lengths.

Pistol length gas systems are the shortest, and they’re about 4” long. A carbine length system is 7” long. Further, a midsize gas system is 9” long and the longest, rifle systems are 12” long. These, as you’ll see soon, correspond to several barrel lengths, and with accompanying pros and cons.

Six Inch Barrels

About the shortest barrel that you can hope to have normal function in an AR is a 6” barrel. These will have substantial accuracy problems because of a short sight radius as well as the fact that the bullet will not get up to normal velocity, resulting in a bullet drop. These will function with a pistol-length gas system and might work for extremely close quarters work, but be careful as you’ll have your hands awfully close to the muzzle at all times.

Ten To Twelve Inch Barrels

With a little bit longer barrel comes a little more velocity: with a carbine gas system, these short ARs can gain some serious accuracy over the extremely short models, but you’ll still notice that bullet drop will start sooner than you’d like.

This is a common length of AR for folks in special forces who know that their mission will take them indoors, as this is a compact weapon that still can reach out to about 200 yards with a little bit of practice. Overall, these are the first reasonable option we think is out there if you want accuracy past room-clearing distances.

Thirteen to Sixteen Inch Barrels

This is, in some regards, the Goldilocks zone for AR barrel lengths, as we’ll develop in the next section. Paired with a Carbine length gas system, rifles with barrels of this length give up very little in terms of velocity when compared to longer barrels but are a little more compact than longer weapons. Additionally, the carbine gas system, balanced with an appropriate buffer spring and weight, are exceptionally soft recoiling weapons, which makes follow-up shots a lot easier.

Twenty Inch Barrels

About the longest barrel you’re likely to see on an AR platform rifle is 20.” These give the greatest possible velocity out of standard 5.56mm ammunition, without being too bulky for people to use in adaptable mission settings. Barrels of this length are less common now but are a good choice for folks who want to stretch the legs of the platform. With a rifle-length gas system, they’re also exceptionally reliable weapons as well, as this is basically the design as it was first developed in the 1950s.

So, What’s the Best Barrel Length?

As with most things in the firearms world, the answer is: what’s your purpose?

If you want the best possible ballistics, then a 20” barrel with a rifle-length gas system is the way to go. Even though these are long and a little heavier than what’s common these days, most accuracy-focused setups will have longer barrels to get additional velocity and a longer sight radius for iron sights.  The M16A1, as issued in Vietnam, came with a barrel of this length and it performed well for troops for years.

Of course, some people don’t want the best ballistics, and they are looking for a handy gun to use in home defense. To that end, a Short-Barreled-Rifle might well be the most effective: a 10” barrel with a pistol length gas system can be highly effective in close quarters and they’re super handy. If it were up to us, we’d also put a suppressor on it to tame the unholy muzzle blast that comes from all of the unburnt powder and unused energy from short barrels.

For most folks, something in between works well. Enter the M4, the standard service rifle in the hands of several million people in the armed forces all over the world. With a 14.5” barrel and a carbine length gas system, the M4 can reach out to about 300 yards with no issue but is also handy enough to be pressed into room-clearing duty in, say, Fallujah. This is what we go with most of the time on our personal rifles.

With all of that said, and government paperwork aside, you don’t really have to choose. It’s entirely possible to have a single lower receiver, a few buffer springs, and a set of uppers that you can change out in seconds depending on your mission requirement. That’s one of the brilliant things about the AR 15 design, and we personally own several different barrel lengths for different tasks.

If you do not have the items you need to get through the day, hunting can be tricky! There are the normal things you need to have on hand like rifle magazines, snacks, extra water, or a small first aid kit. But what are some things you may need that you would not normally think to pack? Forgetting the small things is so easy to do, but it can make a significant impact on the experience you have on your trip. Save yourself some grief and be sure to include the following five things in your hunting pack.

Decoys

Just the thought of lugging around an extra bag or crate of decoys can feel frustrating. However, having a few on hand can increase the amount of game you see in your crosshairs. Either those of deer or of fowl, are made of light materials, but they help your prey feel safer in the area you set the decoy. An important tip to remember is to set the decoy upwind from where you will be. This will help keep your scent from flowing towards the decoy and tipping off the prey of your whereabouts. Decoys look interesting and cause the hunted animals to be curious about who the decoy is (are they from my herd or somewhere else?). If you want to make decoys extra effective, you can purchase decoy smells to add, further luring out the hunted prey. The sense of smell is one that animals rely heavily upon, so adding this layer to your decoys can further increase your daily yield.

Laundry Detergent

You may not think about doing laundry before or after your hunting escapade, but you will if it means further disguising yourself from the animal you are hunting. Wildlife Research Center’s Super Charged Scent Killer Clothing Wash is one of the many options available to kick the nasty scent of “human.” There are body sprays and the like that you can keep in your pack for your trip. However, you will be adding a layer of smell protection when using the detergent, as your clothes will not smell like you, and they will trap in some of the odors that typically emanate from your body. Taking advantage of this will keep animals from suspecting you. Try washing your clothes in a scent killer laundry detergent and you will not be disappointed.

Trail Cameras

If you are new to the hunting scene, you may have never heard of or thought of setting up cameras around where you will have your hunting stand. At face value, this sounds like a lot of work for an unknown yield. However, they can help you keep an eye on your prey, even from a distance. Trail cameras are made rugged so that you can even consider putting them up for extended periods of time, no matter the weather. This gives you the opportunity to plan your hunting patterns on the grazing patterns of your prey. This allows you to create hunting locations based on the areas the animals frequent most. If you have been struggling with your tracking, if you are wanting to bag a certain amount or a specific animal, trail cameras can help you make better plans and properly execute those plans. Investment of time and money will serve you well. Do not let the novelty and the time commitment discourage you from using this helpful tool!

Surveyor’s Tape

Surveyor’s tape or another brightly colored tape or tie off will serve you well in the field. When you make a shot, you want to know you can gather your kill without getting lost in the woods. It can be easy to do, thinking you are on the correct trail then lose sight of both your kill and your stand. This can lead to you heading home emptyhanded. Avoid this tragedy by keeping surveyor’s tape in your pack to brightly mark where you have been. As you follow the blood trail or your trajectory path, put some of the tape on a nearby tree or other standing structure. This will guarantee that you can make it back to your starting point. If you lose track of your kill, you can also go back to the last place you were sure you were on the right track and continue the search from there. Having tape on your person can prove helpful in other situations, too, where you need to tape something back together or ensure you do not lose an item. Brightly colored tape can also be used as a signal to other hunters or emergency personnel in emergencies.

Zip ties

This may be a surprising suggestion, but zip-ties can serve many uses in the field. If you need to attach an extra item to your pack or if a zipper happens to break, zip ties can help you fix that! They can also be useful in tagging your kill or binding up their extremities for easier carry. Zip ties can also be used to help you mark your trek if you run out of or have forgotten your surveyor’s tape. Also, they can help you tie back branches that may be problematic when aiming or looking through your scope. Zip ties are cheap and are easy to use. They are even easier to take apart when you are done with them; just cut them!

Some items on this list may not be what you initially think of when you imagine packing for a hunting trip. However, thinking outside of the box with these items can help you better bag your prey, keep on the trail, and go home successfully. Why work harder when you can work smarter with things like decoys, scent killing detergent, trail cameras, surveyor’s tape, and zip ties? Make it easier for yourself and keep these items in your pack and encourage others to do the same. What are some other out of the box items you like to keep on you?