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AR-15 Buyer's Guide

AR-15 Buyer's Guide

Modern sporting rifles, especially those designed on the AR-15 pattern, have become the most popular centerfire rifles in the U.S., and for good reason. Virtually everyone is making ARs these days. This is great, but to a new buyer, the choices can be overwhelming. We'll take you through the various options available on today's ARs and help you find the features that are right for your needs.

Rails & Forends

This is another area where we've seen the trend come almost full-circle. Inspired no doubt by photos of soldiers overseas, Americans started hanging LOTS of things on their ARs. Carbines with miles of Picatinny rails saw pounds of accessories mounted for every conceivable task. Guns that looked cool online handled like station wagons in real life, and many users started unbolting unnecessary items from their forends.

Another key choice here is whether you desire a free-floating rail. Free-float rails attach at the barrel nut and make no contact with the barrel, which prevents accessory mounting or sling pressure from affecting a bullet's point-of-impact. Free float rails are usually made of aluminum or carbon fiber and are available in various lengths, diameters and configurations. Many of today's forends have deleted the miles of Picatinny rails in favor of the ability to mount small rail sections where needed.

My favorite among this latest generation of forends is the CMR rail from Centurion Arms — it incorporates a top rail and fixed mounting points for sling swivels and a bipod, but it maintains a slim and lightweight overall profile.

If free-floating isn't necessary or where cost is a big factor, traditional forends like the G.I. style handguards or the MOE from Magpul are an outstanding value.


The vast majority of receivers found on factory ARs are flat-top Mil-Spec uppers and lowers constructed from 7075 T6 aluminum. Unless you're looking to replicate the look of the original M-16 or know for certain that you'll never mount an optic, the flat-top design is preferable over the carry-handle style upper receiver.

Some makers, like HM Defense in Ohio, CNC machine their receivers from aluminum billets, which allows them to sculpt the parts with unique aesthetic lines and features.

Gas Blocks

Gas blocks regulate the flow of propellant gasses from the barrel into the gas tube. If you have too much gas, the carrier slams its way into the buffer tube and causes undo felt recoil. If you have too little gas, the rifle won't function properly. In most cases, the fixed gas blocks on factory rifles and carbines function reliably with a variety of ammo and should be left alone. That said, if you plan to use your AR for competitive practical shooting or use it with a suppressor, an adjustable gas block is preferred. A low profile gas block allows more flexibility when choosing forends and is preferable if you plan to use a free-float rail.

The low profile gas block on this JP PSC-11 allows the forend to extend over the block, allowing the shooter more grip area.


Although most users mount some type of optic to their AR, iron sights remain a viable option. When irons are chosen, either for primary or back-up use, the two options are fixed or flip-up. The traditional AR's triangle-shaped front sight post is as durable as it is iconic. If rigidity isn't your primary concern, plenty of excellent flip-up front sights are available from companies like Bravo Company, Troy and Magpul. The rear sight can also be fixed, even on a flattop upper, using unit's like LMT's Tactical Rear Sight. Almost all of these sighting options can be used even if an optic is mounted and can be 'co-witnessed ' for use in-conjunction with many non-magnified optics.

This S&W M&P-15 MOE uses a fixed front and folding rear configuration.

Muzzle Devices

Since the expiration of the Clinton Semi-Auto Ban, most of us are free to use the muzzle brake or flash hider of our choice — state laws vary on this, however. Selection of an appropriate muzzle device is, once again, mission-dependent. In general, I prefer flash hiders to brakes since they don't direct propellant gases in a way that increases noise or blast for the shooter. Choose whatever flash hider suits your tastes — there's nothing wrong with the USGI model. Most of my personal ARs are equipped with Blackout flash hiders from AAC, which allows me to quickly mount a suppressor to any of them — something to consider if you plan on buying a can.

For a 3-gun rifle, a brake is a must, and the blast is a necessary evil. My 3-gun rig wears a giant Benny Cooley-style brake from JP, and muzzle rise is pretty much non-existent.

One other point to consider while we're on the subject: Permanently-attached muzzle devices can be used to extend shorter barrels to comply with the 16 ' minimum length mandated by the National Firearms Act. This allows for the shortest overall length possible without a tax stamp.

The 14.7" barrel with a pinned 1.3" flash hider on this LWRC M6 gets you to 16" and makes for a handy package.

Stocks & Grips

For years, AR owners had the choice of fixed G.I. stocks or the CAR-15 style collapsible units. Today, the possibilities are virtually endless. Stocks can often be removed and replaced more easily by the consumer than many of the components we're discussing, but certain changes can necessitate replacing the buffer tube, which is more involved. The first question is: fixed or collapsible? Fixed stocks can be lighter, slicker and stronger, but dimensions like length-of-pull won't generally be adjustable. One of the great things about collapsible stocks is that the stock's length can be adjusted to fit different shooters (adult, children, men, women) in seconds. Stocks are all about user fit, so it's important that you actually shoulder a firearm equipped with a given stock rather than choosing one that looks cool.

The Rogers Super-Stoc is a versatile choice as it can be adjusted for length and locked in with a lever to remove any "play," which provides the best of both fixed and adjustable worlds.

Grips are easily swapped and generally inexpensive, so find the one that feels right to you. It's also important that a grip fits correctly in any shooting position. If you can, get prone when trying out a grip — it may feel far different than it did standing.

Gas System

Guys who spend more time in front of the computer than they do on the range agonize over the choice between the original direct-impingement gas system and more modern piston designs. Both have their advantages and disadvantages, and both work incredibly well on properly constructed firearms. The 'gas ' guns are lighter, less expensive and function reliably unless you allow them to get very dirty or your carbine wears a very short barrel. That said, if the additional cost and weight don't bother you, good short-stroke gas piston systems like those from Barrett and LWRC are very reliable, especially with short-barreled carbines.

The length of the gas system is also an issue. If your AR doesn't use a piston, it will use a rifle, mid-length or carbine-length gas system. 10 years ago, when M-4 lookalikes became the rage, carbine-length gas systems became pretty much standard (and remain so on military M-4s). That short gas system has its shortcomings though, and it didn't take long for design engineers and 3-Gun shooters to push the trend back to mid-length systems, where possible. Generally speaking, the longer the gas system, the better. Longer gas systems produce a less-violent rearward movement on the bolt carrier, and, therefore, the shooter feels reduced carrier slam during recoil. The longer gas systems can also reduce wear on extractors and result in less fouling inside the receiver. Unless a short gas tube is needed for functional or aesthetic reasons, go with a mid or rifle-length system.

Competition rifles like this Stag Arms 3G use long gas systems to combat excessive muzzle rise.

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