AR-15 Carbine Configuration

AR-15 with SOCOM Boom Tube stock

Don’t short-change a short gun! When you spec a carbine, think about shooting it! Simple? Yes. But don’t adapt to the carbine; make it adapt to you. Here are a few thoughts on how to get the most utility from your carbine.

I get getting a lot of correspondence from folks wanting advice on carbine-style AR-15s. By the way, and to start, these go by numerous designations, but a “carbine” technically is a short-barreled version of a rifle, and that’s easy to picture. AR-15 carbines likewise normally have shorter stocks—usually length-adjustable (collapsible).

Medesha Firearms rifle-length free float tube
This is a rifle-length free float tube from Medesha Firearms designed for use on a carbine-length barrel system. The advantage of the extra length is all shooter-side, but the extra length in no way detracts from the gun’s portability or maneuverability. This forend accepts bolt-on Picatinny mounts that can be placed at all corners of convenience and that’s a good system. It’s compared here to a “carbine-length” float tube.

First, unless you really want a short gun, I can tell you—no, promise you— that a rifle-length AR-15 will be less problematic. The reason for this has virtually all to do with the abbreviated gas port location on a common 16-inch carbine barrel. This results in an overabundance of available propellant gas, which leads to function issues. It’s also a product of the maker’s specifications (gas port diameter), but generally they run “hot.”

Solutions warrant other articles for clarity, but suffice it to say that carbines usually need to be “slowed down” with respect to action operation as the reflexive symptom of excessive gas port pressure is excessive rearward (ejection cycle) bolt carrier velocity, and the bolt unlocking too early. Those are related. I think the more recent “mid-length” gas systems are a decidedly better way to go.

Fixing Up Your Carbine

There’s honestly no reason a well-constructed carbine, from well-respected parts, can’t shoot as well as virtually any AR-15. I do know that AR-15 accuracy pioneer Bill Wylde recorded group after group with 14-inch-barrel guns under 1/2 minute of angle at 500 meters. This opportunity came through contract work with the Canadian armed forces and, of course, Bill built the guns. These were nothing more than miniature NRA Match Rifles— Krieger-brand barrels, free-float forend tubes, and attention to detail in assembly. By the way, the ammo used was Canadian ball. Good stuff if you can find it.

AR-15 forend with tactical flashlight and Vortex flash suppressors
A flashlight is effective in conjunction with iron sights. It runs off a forend-mounted switch. I put Vortex flash suppressors on all my carbines; it’s very effective in reducing intensity of the muzzle flash.

So, yes, carbines can shoot.

The big focus for me has always been getting them to a point where they could be shot.

Choosing furniture matters much. The first is the free-float forend tube. Of course, we’re now assuming we’re going to incorporate a tube, and that’s a right smart incorporation. A tube makes for a stress-free barrel. Otherwise, by the way standard plastic forend halves attach into the front sight housing assembly, pressure directed against the forend influences shot location.

Most float tubes provide Picatinny rail mounts, making it easy to mount all manner of accessory items and, as suggested, there’s no ill effect on accuracy from weighing it down. And if you’re going to load down a carbine with lights and sights and handles and the like, mount them all on the upper receiver or the float tube. Leave the gas manifold be.

Forend length is an option from some suppliers. Go with a longer one, if it fits with the rest of the pieces. The “carbine-length” forends put the supporting hand in such an awkward position that it’s a challenge to shoot well. Increasing tube length lets the hand move farther out and shooting becomes easier.


AR-15 with SOCOM Boom Tube stock
This one showcases what I think makes a good carbine, or did for me. It’s very “shootable.” It’s got my favorite stock, a SOCOM Boom Tube. It’s strong, solid, and comfortable, and that’s why it’s my favorite. The rail covers on the forend make for a nice feel and great hand perch.

The next shooter-side option is the stock. Honestly, and experience will show this if it’s hard to accept straight up, you’ll really not notice a difference in deploying a carbine if it doesn’t have a collapsible buttstock. It’s the front end of the gun that “gets in the way” in close quarters, not the back.

Consider an older A1 stock since it is about a half-inch shorter and therefore a little easier to bring up into the shoulder in a hurry. On the other hand, most folks will want a collapsible stock to make the gun a shorter package for transport or storage, and, of course, because they look cool.

The traditional Colt-style collapsible has to be one of the worst stock forms yet conceived. It’s uncomfortable. Aftermarket tricks and treats make it more shooter-friendly, and there are a number of length options available that can be exploited. My choice is an accessory replacement.

I’m not a big fan of any manner of complexity on a practical-use rifle. I always think about suffering disaster in a worst-case circumstance before I consider revving up performance for a small operational advantage under casual circumstances. It’s easy to be happy with things such as extended bolt-stop releases, oversized ambidextrous safeties, big magazine release buttons, tricky charging handles, and the like when out on the target range, but such things snag and frequently break, and, yes, can even function unintentionally. If you purchase any such contraption, make double sure it works, and judge its construction and operation within the system critically. Increasing a part weight, for instance, as can come with an oversized bolt-stop release, backed by a standard spring and geometry may not operate as crisply, or smoothly, as the stock part.

Older Colt AR-15 rifle
This rifle showcases a lot I don’t think makes for a good carbine. It’s an older Colt-brand. Light, simple, but hitting targets quickly with it is a challenge. Think about what a carbine may be asked to do and consider the value of shooter-side enhancements. Hitting the target always comes first.

I run only 20-round-size magazines, not 30s. The gun is easier to handle with the shorter mags.


I run irons. It’s a big help to move the front sight ahead if possible so it’s easier to focus on, and mounting a clamp-on-style front sight on a sturdy forend works well. Just make sure mounting heights are congruent so the front and rear co-witness. And don’t go too high: it’s already difficult to get the head down on the stock; don’t make it impossible.

Most prefer some manner of optic. Optical sight selection is a topic for another discussion, but just make dang sure to keep the batteries fresh. By the way, a flattop upper configuration is the only thing that makes any sense. A carry-handle-style clamp-on is easy enough to add for those who want it, but a flattop provides far more flexibility in sight mounting.

Carbine or full length? Do you have tip for tuning or decking out your AR? Share it in the comment section.

The preceding is a specially-adapted excerpt from the book The Competitive AR15: Ultimate Technical Guide by Glen Zediker and Zediker Publishing. For more information visit and to purchase go to

Glen Zediker has worked professionally with some of the greatest shooters on the planet, as well as leading industry “insider” rifle builders, manufacturers, and proven authorities on gunsmithing, barrelmaking, parts design and manufacture, and handloading. And he does pretty well on his own: Glen is a card-carrying NRA High Master and earned that classification in NRA High Power Rifle using an AR15 Service Rifle.

About the Author:

Glen Zediker

Glen Zediker is the owner of Zediker Publishing, which specializes in books and other publications focused primarily on AR-15s, handloading, and shooting skills. Since 1989, he has authored or co-authored 20 books.

He started shooting at age 5 and competing in NRA Smallbore rifle at age 8. He got his first AR-15 at age 15 and has now had 45 years of experience with that firearms platform. He’s worked professionally with some of the greatest shooters on the planet and leading industry professionals. And he does pretty well on his own! Glen holds a High Master classification in NRA High Power Rifle and first earned that using an AR-15 Service Rifle. He’s also competed in many other forms of competition, including USPSA, Steel Challenge, Silhouette Rifle and Pistol, Bullseye Pistol, ISSF Air Rifle, Practical Rifle and shotgun sports.

Since 1986 Glen has been a frequent and regular contributor to many publications, having had over 500 assigned articles published. See more at
The Mission of Cheaper Than Dirt!'s blog, The Shooter's Log, is to provide information—not opinions—to our customers and the shooting community. We want you, our readers, to be able to make informed decisions. The information provided here does not represent the views of Cheaper Than Dirt!

Comments (13)

  1. Great article. I have a custom built AR that is for target shooting. But have been think about a build that I want to do so thanks for the article a lot of helpful information.

  2. Give me a good trigger and optics and I’m good to go. for my intended use, all that other stuff is just bling…just my opinion.

  3. Great article love black rifles free floating or floating any rifle barrel will make it and you a better marksman and the sky is the limit when it comes to customizing your build or factory built rifle semperfi

  4. My last build included a six position collapsible Daniel Defense stock with a Law Tactical folding stock adapter. This makes the transportation of the carbine easier, though it does add a little weight and you can’t fire with the stock folded.

    My next build (or maybe an upgrade on this one) would be a side charging upper.

  5. All I have to say is that I love this silly “evil” platform. I never really got into seeing how many things I can attach to mine. Ran a LWRC carbine for years and decided that I preferred the iron sights, always ending up taking off my EOTech.
    Granted I wasn’t hitting consistently out at 500 yds, but that’s the challenge isn’t it?
    Decided I’d try to build one… WOW, not hard at all and damn fun. Now I know exactly how they work, run, and where the hotspots are. And to me, that’s just as important as knowing how to shoot it!

    Great article. Would love to see more like this.

  6. Thanks for the article. Am always happy to read info and others “take” on rifles, pistols, and anything FIREARMS.
    My only pet peeve and this wasn’t mentioned in your article, but due to this forums audience, I would just remind everyone not to call these rifles ( AR-15 type) “Assault” weapons. I do actually see them listed that way in the newspaper ads!
    Thanks everyone for reading.

  7. A very reasonably written article. Yes, the six position collapsible stock is uncomfortable. I put a soft rubber extension’ on one. You’ve seen them because they have the armor symbol on them. When I build an AR, I prefer 18 inch barrels with Vais muzzle brakes so I use a mid-length system and have never had a problem. As to the length of the free float quad rail: Since I use nothing but flat top uppers, with the rail thereon, I use carbine length free float quad rails because I have plenty of room for a 3 x 9 scope, a front sling mount and a foldable handgrip on the bottom AND it keeps he weight down as well. I wish that some manufacturer would come up with a hardened plastic, (spelled nylon), free float quad rail! Although I like the quality of my SS 6.5 Grendel barrel from Lothar-Walther, it weighs more then a Chrome Moly barrel would so my current build in .308 will be a fluted chrome moly. I did purchase a Sop-Mod stock because of its “battery compartments”. If the finished product is too light for the recoil, I can use mercury recoil adjusters. A little trick that we used to use in our national match M14s for the Forscom Matches.

  8. You didn’t talk about caliber, but I really like .300 Blackout, which you can make from .223 brass for reloading. Heavy, sub-sonic rounds, especially when combined with a “can”, make it a pleasure to shoot.

  9. By preference, a full length AR-15 would suit me real fine, If I remember correctly, the AR was optimally designed for a 20 inch barrel. Also, the longer barrel fully utilizes the gas pressure for optimum operation. Needless to say, but the longer barrel facilitates the range and accuracy of the weapon.

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