The AR15 carbine has been a popular rifle since its introduction. It is handy, easily carried, reliable, sufficiently accurate and gets the job done. It is like an extension of the person carrying it. Building a carbine is easy but there are some new things to consider. Sadly, one has to do with the rather silly law about so called assault rifles. The Pre-ban rifle was no more deadly than the post ban, but politicians always feel the need to look like they are doing something to save mankind from itself, so the ban exists and must be considered when building a carbine. This is less an issue with a full length service rifle, as flash is of little concern - if you happen to want to compete, the loss of the flash suppressor is actually a plus for accuracy! But with the shortened barrel of the carbine, flash and report are increased and frankly, you are best off purchasing a full size pre-ban rifle and just building a carbine upper to augment it. You can usually find a pre-ban rifle, purchase an assembled carbine upper from a parts house, and still pay LESS than what you would pay for a pre-ban carbine. I recently saw several pre-ban AR15A2 rifles in the $840 range and saw a few AR15A1 police cast off's for much less. A carbine of the same era can go for as high as $1300. This is a rip off of course and no more than price gouging. I can find little justification for this high price. Therefore the reason for this article. BYOR. Build your own rifle.
Trying to build the ideal post ban carbine is problematic. You have to resort to muzzle breaks that are pinned permanently to the barrel and this is less than ideal for several reasons listed in Part 1 of this series. Also, with the short length of the barrel, muzzle blast is already loud. Adding a muzzle break to it will increase the amount of noise the shooter suffers. I recently spent some time next to a post ban ArmaLite rifle with their proprietary muzzle break. It was painful to lay next to and I finally had to get off the firing line in disgust. I have since come to believe that having a normal exposed crown is a better alternative to a permanent muzzle break. It is not as if the 5.56 NATO round has any recoil to worry about anyway. If you want a decent carbine I feel it is worth locating a pre-ban rifle for this project when compared to accepting the compromise forced upon us when trying to make a post ban carbine. I will cover your post ban options at the end of this article.
If you already have a pre-ban AR15 you are in luck. This will allow you to swap uppers and create a tactical carbine and swap back when you need the long rifle. The pre-ban rifle, to the best of my knowledge, is grandfathered and you can still install a collapsible stock on it. Check the LAW to be sure. The carbine owner will need one more tool. It is very inexpensive. About $8.00. It is a small metal handle with a finger on it and it is used to remove or install the collapsible stock. If you are sharing one receiver for a long rifle and a carbine this tool is a must for switching the stocks back and forth. You can get the collapsible stock off without it, but not without marring the finish.
Assuming you are legal (pre-ban) and good to go, getting a carbine upper is easy. Any number of sources have the necessary parts. We will list the various sources below. You can buy complete upper assemblies, complete carbine kits which have all the parts for the entire rifle minus the lower receiver, or you can purchase carbine barrels to install on your current upper. The options are endless and you can make a carbine in just about any configuration you want.
When ordering a new upper, do not forget to order a NEW bolt. You CAN order a complete carbine upper without a bolt carrier group to save money, but you should always have a dedicated bolt to match each complete upper assembly. This is a must. As the bolt wears in to match the chamber in which it is being used, it will no longer headspace exactly to another rifle's chamber. It "may" be usable for a time, eventually it will wear in a manner that will allow excessive headspace in another receiver, particularly if you shoot a lot. Spend the money on a new bolt. It is your face. Lets try to save it!
Do you want a tactical carbine? A plain old carbine like the XM177? A carbine for room entry practice? You have seen several options available. Not all Carbines are the same. A Flat Top carbine will allow a large amount of versatility, as you can mount countless optical devices and iron sights. An A1 style upper is a good inexpensive shooter that will work for room entry and limited long range. An A2 type upper gives you more range with its iron sight versatility. My personal feeling is that the Flat Top upper is the only way to go. With it you can configure the rifle for room entry, basic infantry type shooting, medium range tactical shooting (with the appropriate scope) or just out and out plinking. The point is, by design the Flat Top upper allows you to reconfigure the rifle as your needs change. While both the A1 and A2 upper will serve your needs, the Flat Top will do this, and then some.
We will assume here that you are limited to a 16" barrel to stay legal. Will you be adding lights, optics, or other tactical gear? There is a wealth of aftermarket and surplus equipment that attaches to the AR15 rifle. Some of it is next to useless and needn't be considered. I rate the 37mm M203 lookalike as one of these. Looks neat. But that is about it. I recently saw a flare fired from one of these things and it went all of 40 feet up and 50 feet down range. Worse than useless. My point is, think long and hard before spending good money on a neat toy that you will have zero actual use as a civilian or police officer. If you are not dumping CS gas into a drug house, you do not need to blow money on the M203 attachment. This will also help you out in another area: money.
The M4 is the latest version of the AR15 carbine. It is the most versatile and handy to date. With its flat top upper, you have a choice of sighting systems. Kits exist today that include contract M4 upper assemblies. They are somewhat expensive and I would make the case that they are unneeded other than as a unique collectors piece. Why? If you have no plan or need to mount an M203 you have no need for the M4 barrel with its reduced diameter cut aft of the flash suppressor. When you compare the average price of a real M4 upper assembly to an equally effective carbine upper, it becomes harder to justify the difference. For example, a 16" M4 upper assembly may go for anywhere from $500 to $650 depending on dealer. A regular and complete flat top carbine upper assembly with a relatively accurate 16" heavy match barrel (1:9 twist) with an M4 handguard will go for about $300. The only difference between the two will be the lack of a cut in the barrel for the M203 attachment and the heavy barrel of the carbine. In a way, you are getting a better barrel with the Non-M4 upper, for less money. If you want a normal A2 upper and no M4 handguard, expect to pay $260 for a complete upper assembly. Personally, I will never have a carbine without the standard M4 handguard. Once you try it, there is no going back.
The larger handguard does away with the main reason the older carbine was somewhat of an annoyance. With double heat shields and a large surface area, the M4 handguard allows you to shoot all day without ever feeling the sting of barrel heat in your hand. The older style grip was next to useless in this department. It was small in diameter and often came without any shielding whatsoever. Extended shooting left your hand covered in sweat and often allowed enough heat to pass through that continued shooting become very uncomfortable. No matter what you decide to build, tell the dealer you want to delete the "shorty" carbine handguard and replace it with a real M4 handguard. You will be very glad you spent the extra money. These run around $40. More from those who wish to gouge. Other handguard options include short aluminum free float tubes and a specialized handguard similar to the M4 but that accepts a wealth of attachments. This one is not particularly comfortable to use but it does have the advantage of multiple uses. Unless you are in some sort of special operations unit, you needn't waste you money on this one.
A flat top upper receiver gives you unlimited options. But be forewarned, if you plan on having the detachable carrying handle/rear sight as a back up, you might find it impossible to zero the rifle unless you get a handle specifically matched to your barrel - in other words, buy the handle from the same people you purchased the upper receiver and barrel from! Many of these detachable handles will not work with the front sight bases from another manufacturer. It appears that the handles some people are offering are too high in relation to the front sight base and the result is that you can never get your point of impact down to the point of aim. Either the handle is too high or the front sight base is too low. I can not offer a fix for this as I have yet to find a set that works. Every front sight base I have measured - from several manufacturers - has been almost of identical height, but the various detachable handles vary slightly in height. I could get none of them to zero low enough at 25 meters. Eventually I said to heck with it and decided to forget about this handle altogether. Ask about this problem specifically when you order your upper or parts kit. My ArmaLite A2 style handle will not allow me to zero at 25 yards on my mil-spec Flat Top upper. It "may" work on an ArmaLite built upper. I can not say as I do not have one. This problem is well known to shooters but whenever you ask a dealer about it, they look kind of clueless. I do not know if there are different front sight bases on the market, or if the handles themselves are all of differing heights. All I know is that with several different handles the best I could do was get six inches high at 25 yards. As my latest Carbine was built to work as a means to practice room entry and team tactics, I didn't give any more thought to this issue and mounted instead the excellent Aimpoint Comp M.
The flat top upper allows you a large variety of optics. Some things to consider: If you plan on using a rifle scope, you will need to get high or extremely high ring mounts. If you try to use standard or regular height rings you will find that you have to lay your head over the stock to get a good sight picture. This is neither comfortable or conducive to good marksmanship. Even though you are shooting a carbine, possibly at close range, you still want to be able to maintain good shooting form. Do not expect to mount a standard Mk4 ring on a flat top upper. Do not allow anyone, no matter how well known, to convince you otherwise. I know of one builder who markets a tactical carbine who uses very low rings on his carbines. You just about have to retract your head into your shoulders just to get low enough to see through the scope! And for this discomfort he'll charge you several THOUSAND dollars! Purchase the high or extra high ring set. If you already have a set of standard rings, you can buy an inexpensive riser that will lift the center point of the scope high enough to be functional.
Optics range from combat sights to sniper scopes. All can be utilized on a carbine and all have different purposes. My favorite, as stated above is the Aimpoint Comp M or ML. This particular red-dot type scope has a small 3 moa dot and is very good out to ranges that amaze me. The smaller dot allows you to see the target clearly as opposed to some of the other scopes of this type with 7 moa or larger dots. Other excellent options include the AGOG Reflex, the ACOG 4x32, and the ELCAN. All have slightly different uses. Research will show which fits your needs. For close-in work, I felt the Comp M made a lot of sense as you can shoot with both eyes open for total awareness of your surroundings.
Police Marksman looking for a good backup or lightweight tactical rifle would of course want a more normal scope of higher magnification. Any number of variable scopes could fit this need. As the ranges are reduced, I'd go with a plain duplex reticle.
For general use a chrome lined barrel is the best option. This is in direct opposition to how I feel about a rifle designed for maximum accuracy. The carbine, while capable of extreme accuracy, is not generally used for sniper ops. It can be used this way, but only out to limited ranges. For the average user, who plans on shooting a lot with minimal maintenance, the chrome barrel is the way to go. Twist rates can be had in 1:7 and 1:9, unless specified otherwise. A rate of 1:9 is the most popular and available. A twist rate of 1:9 will allow the barrel to last much longer than the fast 1:7 rate. There is little reason in fact to go with a 1:7 twist for this project. A 1:9 twist rate will stabilize 50 grain bullets all the way up to 75 grain bullets. Barrels come either in a heavy configuration or in the old lightweight configuration of the AR15A1. I prefer the heavy option. It is more versatile and allows you a certain amount of abuse in terms of sustained fire. It also balances out the rifle nicely without adding much weight to the overall package due to its short length. The carbine in this configuration is not designed for total accuracy. It is a good backup, or spotter's rifle. It is a great entry team rifle. It needn't drill 5 rounds into a half inch at 100 yards. Used on an ERT (SWAT), it may never be used against someone farther than 20 yards away, but is capable of body hits beyond 300 yards when required. A tactical carbine is versatile if nothing else.Precision use
For a scoped precision carbine, you should look for a good stainless steel match barrel. A 1:8 twist is ideal but 1:9 will do. Plan on utilizing a free float tube. While is it not necessarily needed on such a short barrel, the extra cost is minimal and this will allow you to use a straight taper bull barrel. Configured this way and topped with a good piece of glass, the rifle can be very accurate and serve well for close range work (100 to 300 yards). It is far superior for police work than the Ruger Mini-14. Its accuracy is superior to the Mini-14 and its ergonomic design is better suited as well. The Ruger, while well represented in local law enforcement, has nothing to offer over the AR15 carbine.
There are many attachments for your carbine. Lights seem to be the most popular. Of these, the Sure Fire systems are probably some of the best. There are too many to list, but you can get these in just about any configuration you desire. Beside the barrel, under the barrel, attached to the handguard. Laser sights are another option. I am not a great fan of these, particularly on handguns, but if you do your research, you'll no doubt find one that fits you needs.
When employing a carbine the standard sling attachment points are not always ideal due to their location on the bottom of the rifle. With the collapsible buttstock, which moves the rear sling mount to the side, you will want to locate an M4 side attachment for the front sling mount. This devise slips between the barrel and the front sight base and moves the sling mount to the side. It runs about $30. The alternative is the "paper clip" style assault sling clip that attaches to your front sight. It is nowhere near as nice as the M4 design. It rattles and can even get in the way of your sight picture. As a field expedient system it works, but it is not ideal.
Above I stated that a post ban carbine is not ideal, but I will say that a post ban carbine can be built. I recommend immediately FORGETTING the silly non-collapsible type buttstock that looks like the pre-ban collapsible stock. What's the point? Better to use the short AR15-A1 stock with the trap door compartment. Even the longer A2 stock can be used. This is not ideal in terms of a weapon for room entry and team tactics practice, but it will certainly be more comfortable to shoot and have the option of storage space. The longer stock is ideal for those planning on attending an outdoor carbine course. In one of these classes you do a lot of position shooting and the regular buttstock is better suited to this anyway. A fixed collapsible lookalike stock just doesn't seem worth the price. It is akin to buying a Ferrari without an engine. What's the point? I rank this stock as one of those useless gimmicks sold to the easily impressed who care nothing for actual function. I am sorry if this offends some of you, but I do not believe on buying something just because it looks "mean". That method of gear selection seems childish at best, downright stupid at worst. If it doesn't DO anything, there is no point to using it. If you have to build a post ban carbine use a normal stock. At least you will have the comfort of shooting the standard stock.
If you plan on building a post ban carbine with an A1 or A2 stock, make sure you specifically order a post ban upper assembly. If you do not specify this, you WILL get a pre-ban upper. You can modify the pre ban upper by cutting off the bayonet lug and having a cap installed on the threads of the barrel where the flash suppressor would go, but to be legal you would have to have that cap pinned on. Why go to the trouble? Just get a post ban upper assembly with a target crown equipped barrel. Muzzle flash will be greater than if you had a pre-ban, but it is not unacceptable for civilian use. A post ban carbine will still give you a handy and short rifle even if not ideal for some (admittedly police or military type) applications.
I will use prices from M&A Parts Inc. for this tally. Bushmaster or ArmaLite will cost more. I will present some options be stating ADD this part or that. This means that you will request that the parts distributor delete an unwanted item from the kit and does not charge you for it. The new price is derived by subtracting the price of the deleted item from the price of the wanted item. Example: A CAR handguard cost $15. And M4 handguard costs $40. By deleting the CAR handguard and replacing it with the M4 handguard, your cost above the base price of the kit only goes up $25. In short, do not PAY for a part you do not need!
If you have a stripped pre-ban or post ban lower:
If you already have a complete rifle and want a carbine upper, a complete Carbine upper assembly will cost $260. To compliment this you might wish to purchase a collapsible buttstock, assuming you own a pre-ban rifle.
For special barrels you will have to shop around. 16" precision stainless barrels will add substantially to the price of this conversion. A free float carbine handguard costs $35 from most distributors. If you use a bull barrel and the special gas port, you could theoretically use a full length free float tube. Whether this is desirable is up to you, but it would allow the use of a bipod if you wanted to.
In closing, the AR15 carbine is an accurate, handy rifle that can be modified for many roles. It is the true modular gun. Building one can be as simple as adding an extra upper assembly to your current rifle, or as complicated as building a rifle completely from scratch - which, due to the way the AR is assembled, is not hard at all.