With today's technological advances, there are numerous options with how you can set up a defensive carbine. From the lower, the upper, barrel, pistol grip, buttstock, optic, muzzle devices and accessories where does one start? In this article we’ll be going over the basics on what to look for when purchasing and building a carbine style rifle. To keep things simple and linear, I’ll only be writing about carbines in the 5.56/.223 size cartridge. With that being said, I have nothing against other size cartridges, but my personal knowledge base relates more to the aforementioned cartridge. To start this off, we’ll first talk about the upper of the AR rifle first and work our way down.
The first thing you’ll notice on an AR style rifle is a device attached to the end of the barrel (muzzle), the barrel itself and the method of how the gas is being cycled in the rifle. When it comes to choosing what barrel to use on your rifle, you first and foremost need to look at it’s overall application. Are you buying it for competition matches, long range or general SHTF scenario? First off, when it comes to barrel length once you dip below 16 inches, you will then have to apply for what’s called a “Tax Stamp” by the ATF as it’s considered a “Short-Barreled Rifle.” In my experience of teaching and seeing first hand accounts of them being used, unless you half a legitimate reason to have a SBR I wouldn’t worry about buying on. Other than the “cool factor” the smaller barrel you go, the less accurate your rifle becomes and the more of a chance you have of receiving a malfunction. It’s fairly obvious as to why the length will affect accuracy, as for the malfunctions it comes down to how the gas system cycles. When the M-16 was originally designed in the mid-1950’s by Eugene Stoner, it ran on a direct-impingement gas system with a 20-inch barrel. As the years progressed, there was a need for a smaller weapons platform. Currently, there are some companies out there that sell a 6.5 inch AR-15 barrel or complete upper. This is mostly used for protective security work where a 5.56 size cartridge is needed to be carried inside a vehicle. With such a small barrel size, the gas system is obviously smaller as well. The downside to this, is that there is more of a chance for the bolt to not cycle properly. If the bolt doesn’t cycle properly, neither will your ammunition.
As for the composite makeup of your barrel, you have cold-hammer forged and mil-spec. The former affords the user a more durable and tougher barrel especially if you intend to use it often. The downside is you could pay up to $100 more due to the cold-hammer process. Next is the profile (aka weight) of the barrel. The basic three categories are lightweight, government and heavy. If you’re looking to build something specifically for competition where speed and accuracy is vital for mission success, I’d look at the lightweight. Personally I utilize a government style barrel because it’s the happy medium of all three. The heavy style barrel is more utilized for a precision style rifle build where you’re not going to be running and gunning. Along with makeup and weight, the lining of the barrel also needs to be taken into consideration. The two that you have are chrome lined and stainless-steel lined. The former is the most common because it’s less expensive, protects against friction/heat, easier to clean and prevents corrosion. The downside is it’s a limiting factor for ammunition if you’re attempting to utilize it for distances past 300 yards. A stainless steel (aka match) barrel is great at extreme distances, but is more susceptible for corrosion. In my opinion, unless you’re overseas dealing with extreme environmental factors there’s no reason to not spend the extra money for a better quality barrel. The final aspect is the twist rate of the barrel. This relates to how many inches after the round is fired that it takes the bullet to make a full rotation. The smaller the twist rate, the more accurate the bullet can be. The most common is 1/9, but the preferred is 1/7. Anything bigger than 1/9 you should avoid as it will take accuracy out of the cartridge.
When it’s all said and done, the context and application of use is of the utmost importance. Don’t make your choice on fad’s or what “X” is using. It should come down to your lifestyle and funds available as to what kind and size of barrel to choose. In part two, we’ll get into more topics such as muzzle devices, gas systems and much more.