Thursday, October 13, 2011
Jeff Chudwin
In many police agencies, the patrol rifle is carried daily, just like an officer’s duty handgun. It’s another tool to have when needed. As with any life-saving gear, the patrol rifle must function properly, and the best way to plan ahead is to know the common issues surrounding patrol rifle malfunction. As my friend is found to say: “Murphy’s Law isn’t Murphy’s Suggestion.” Things will go wrong at the most difficult and dangerous times. To reduce the risk, you need to be prepared.
For the past 20-plus years, I’ve had the privilege of working with some of the finest firearms instructors and trainers out there. Many are also gunsmiths, rifle builders and shooters of the highest order. Together, we developed patrol rifle end-user and instructor classes. Along the way, we acquired valuable information, with every class being a learning experience for each of us. Some of the things experienced by our student officers forced us to rethink what we believed and at times change course.
Nowadays, it’s rare to see officers use anything other than an AR-15/M16 patrol rifle. That being the case, I’ll review the issues of the AR-15/M16 in terms of use as a police patrol rifle and the three vital design issues that can create operational failure.
(Note: If you don’t have the knowledge and training to perform the following work on your rifle or carbine, bring this information to a trained department armorer or gunsmith and have it explained to you or have the work done. Also make sure you comply with department policy regarding firearms work and modification. Get the changes you need but don’t get yourself in trouble.)
Issue #1: Extraction & Ejection
Of all the mechanical failures we’ve observed in this rifle system, failing to extract a fired or empty cartridge case is at the top of the list. Normally, when the AR-type rifle is fired, the bolt unlocks and begins to move to the rear. The cartridge case is then held onto the face of the bolt by the extractor, which, like a small claw, begins to pull the casing out of the chamber. The casing is then ejected and a live round can be chambered in the feed cycle.
During malfunction, too often the extractor spring doesn’t have sufficient power to hold the fired casing in place. When this happens, the bolt carrier cycles backward and the casing falls away from the extractor and becomes loose in the feed way. Then the bolt carrier group cycles forward and tries to feed a live round from the magazine into the chamber. The live round is blocked by the empty or fired casing, creating a double feed. When this happens, you have to clear a serious malfunction and that requires unloading, clearing the double feed and then reloading. This process isn’t fast, and it’s definitely not something you want to have to do when you’re under attack.
Not knowing the most common cause of this problem led some to make claims of bad ammunition, bad magazines and lack of rifle maintenance. Then about 10 years ago, I met Mack Gwinn of MGI Inc. and he educated me. He told me about the AR-15/M16 extractor upgrade he helped develop and market—the Extractor Defender or D-Ring.
It’s a tiny polymer, “D”-shaped piece that’s simply slipped over the top of the extractor spring when the extractor is removed for cleaning. It takes only two minutes to insert, adds four times the extractor tension and holds an empty casing like a vise. No fuss, no muss—the problems we experienced in every class were gone. My friends didn’t believe me, but then they tested it too and saw it used in hundreds of AR-15/M16/M-4 rifles and carbines that fired hundreds of thousands of rounds, without a single extraction problem.
The proof is clear: The D-Ring works as advertised. There are some who use an O-ring for the same purpose. Although the O-ring is less expensive, I opt for the D-Ring. As one of my instructors (master gunsmith Ned Christiansen) says, it’s a purpose-built part designed solely to cure the ejection problem. ITOA Corporate member Shore Galleries carries the D-Ring. In fact, every AR type rifle sold by Shore’s has one installed. Buy one for your AR-type patrol rifle—it’s a lifetime part. I won’t allow a rifle on the street without one installed.
Issue #2: “Popped Primers” & Chamber Dimension
The AR-15/M16 with a military spec barrel should be able to fire commercially loaded .223 Remington and military 5.56-x-45-mm ammunition without a problem. Much of the ammo for training and street-use is military spec ammo, such as Federal XM-193 55-grain full-metal jacket (FMJ). The FMJ .223-commercial and the 5.56-mm rounds look the same, so what’s the problem?
The issue is that the military ammunition is loaded to a significantly higher velocity and causes higher chamber pressure when fired. If your barrel is chambered using a .223 Rem chamber reamer, the bullet travels .085 inches when fired before engaging the rifling. The distance the bullet travels before hitting the rifling is called the “leade” dimension. If the barrel chamber is cut for the 5.56-mm ammunition, the bullet travels .162 inches before contacting the rifling—the leade being twice as long. Seems insignificant, but it isn’t.
When the military 5.56 round is fired in the .223 chamber, the shorter leade creates much higher chamber pressure and the result causes the base of the cartridge case to expand. When this happens, the primer in the base of the casing can fall out when the empty casing is extracted and ejected. We call these “popped primers.”
Too many times, I’ve seen the primer fall into the lower receiver and wedge under the trigger, putting the patrol rifle out of service until disassembled. Even worse, I’ve seen this happen to a semi-auto carbine, and when the officer attempted to engage the safety, the rifle fired three rounds full-auto. The primer had fallen into the engagement area of the hammer, selector and trigger, creating a dangerous mechanical failure.
One police agency complained that the ammunition from a well-respected producer was faulty because it was causing numerous “popped primers” in their patrol rifles. It wasn’t the ammo at fault. It was the chamber dimensions of their carbines. When the chambers were checked with a special gauge that Christiansen developed after our class had problems, the barrels were found to be .223 dimensions even though the manufacturer claimed they were 5.56 (see photo at the right). As Christiansen instructs our officers, most companies don’t make their own barrels and many have no idea what the true chamber dimensions are. Most of the high-end companies know exactly what their barrel dimensions are and mark accordingly.
If you experience “popped primers,” you have a serious problem that can shut down your rifle. To remedy this, call your manufacturer or a knowledgable gunsmith and they should see to it. But unless you have access to Christiansen’s AR-chamber gauge, you’ll have trial by fire. Every rifle in our classes is checked. If out of spec, we then use Christiansen’s companion chamber reamer to correct the dimension. It’s a very simple hand tool that does the job in less than five minutes.
Issue #3: Loose Carrier Gas Key
The round tube on top of the bolt carrier is called the carrier key. It’s held in place by two Allen screws. If they come loose, the carrier key breaks loose and the rifle begins to “short cycle.” There isn’t enough gas pressure to allow the rifle to operate properly and it fails to function.
A simple test when field stripping the AR-type rifle is to grasp the carrier key with your fingers and try to twist it. If there’s any movement, it’s vital that it be reattached with a thread locker compound and staking the screw heads. I’ve seen this far too many times in recent years. Some of the manufacturers fail to do any staking of the gas key screws. Officers often say that they haven’t had a problem. I add the word “yet.”
In our last class, a rifle checked on day one, failed on day three. The gas key screws hadn’t been properly staked, came loose and the rifle wouldn’t fire more than one round without malfunctioning. The answer is once again from Ned Christiansen, who developed a pocket tool to solve the problem—the Moacks (I’d requested that Christiansen invent the “Mother-of-All-Carrier-Key-Stakers”, see the below photo). This simple and effective tool properly swages the metal screw head so it won’t move under great pressure and stress.
In Sum
These three simple issues can spell the difference between an operational patrol rifle that may save your life or that of a malfunctioned and useless one. You can easily install a D-Ring and check for a properly staked gas key. Chamber issues can be solved through the manufacturer or by specially designed tools. The answers are out there, you just have to know the right questions.
