AR-15/M4/M4A1 Carbine Reliability Issues: Why They Occur, and Why They’re Our Fault!

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Why M4's have reliability issues…and why it's our fault!

By Michael Pannone

December 24, 2008

I fired 15,000 rounds through a semi-automatic M4/M4A1-type direct-gas-impingement (DGI) carbine in 31 weeks without a single malfunction attributable to anything except bad ammunition or bad magazines, with a grand total of 9 malfunctions. The least number of rounds fired between cleanings was 960 rounds, and the only parts replaced were gas rings at 8,860 rounds. And you can, too.

The M4/M4A1 Carbine (and civilian-legal tactical AR-15 carbine) is simultaneously a much beloved and much maligned rifle. But why? It’s beloved because it is so simple to maintain and ergonomically the best-designed assault rifle/carbine system of all time. It’s maligned because many have not maintained it as they should, and reliability has subsequently suffered. If the M4/M4A1 is properly maintained, and a reasonable amount of lubricant is put on it, it is extraordinarily reliable.

We need to…

define “maintained” or better yet, redefine “weapons maintenance”. Through the years “weapons maintenance” has meant “weapons cleaning” with little if any emphasis on inspection or parts replacement. “Vehicle maintenance” is not “vehicle cleaning”, although cleaning is an element of vehicle maintenance.

The true definition of Weapons Maintenance is: maintaining the reliable operation of the weapon through inspection, cleaning, AND parts replacement.

The parts that need inspection and replacement periodically to maintain optimum reliability are those most related to feeding, extraction and ejection, and most prone to wear or fatigue. This includes magazines, especially. If we remove magazines from the equation as an extremely problematic item, the remaining parts critical for inspection and routine replacement are the extractor and spring. From my experience they are the biggest culprits in M4/M4A1 malfunctions, aside from bad magazines.

The rifle at the individual level is often extremely well cared for. But, at the unit level, it is routinely and even institutionally neglected. Think about it. When was the last time a unit went through all its rifles pre-deployment and replaced the extractor and spring and the gas rings? When do units “overhaul” the guns? By “overhaul” I mean gauging the barrel to check remaining life and overall serviceability and replacing the extractor and spring, ejector and spring, gas rings, and buffer spring. Do they issue new magazines for soldiers to take into combat on each deployment?

These parts, to include magazines, are the most common reasons for failures. And yet, as an institution, the military does very little until the gun actually stops working! Rifles are shot until they break for lack of a better description, and magazines are used and reissued many times even when unserviceable. This doesn’t end until someone crushes them so they cannot be reissued. This is the functional equivalent of driving a vehicle until it breaks down before getting it serviced. It may sound like an exaggeration, but many reading this know it is, in fact, more the rule than the exception. And it has to change.

I was one of the first primary instructors on the U.S. Army Combat Applications Training Course with the Asymmetric Warfare Group (AWG). I helped write and structure much of the content and worked with Cav units, Brigade Support Battalions, Airborne and Airmobile infantry units, as well. Each of these units exhibited two specific traits:

1. The soldiers did not really know how their weapons worked (direct impingement theory) or didn’t work (why malfunctions happened) nor how to remedy malfunctions other than using immediate action (SPORTS).

2. There was no specific overhaul schedule prior to deployment to Iraq or Afghanistan.

I have personally fired 15,000 rounds through a 14.5” civilian semi-automatic M4 (Noveske 14.5” N4 VTAC Combat Carbine with Crane O-ring from a SOPMOD bolt upgrade kit and Sprinco 5-coil extractor spring) in a 31-week period with 6 malfunctions and 3 failures to fire. All were attributable directly to bad magazines or bad ammunition. The only parts replaced were gas rings at 8660 rounds and that was preventative and not required. The rifle was still reliable. The rifle was minimally maintained. Each morning of use it was lubricated with 6-10 drops of Sprinco Machine Gunners Lube and a bore snake run through the barrel. Detailed cleaning was done at the following round counts:

1. 1150rds
2. 2110rds
3. 4210rds
4. 5940rds
5. 8660rds
6. 11,745rds
7. 15,000rds

1. 06/10/08 double feed ( personal magazine marked #7)
2. 06/11/08 double feed ( personal magazine marked #7)
3. 06/19/08 double feed GI magazine w/ black follower (unmarked student magazine)
4. 08/02/08 double feed ( personal magazine marked #8)
5. 08/02/08 case separation with reloaded 55 grain FMJ 5.56mm
6. 08/10/08 double feed with GI green follower magazine (unmarked student magazine)
7. *08/10/08 failure to chamber and lock (2 rounds) dud (1 round)

Author's Note: While at XXXXX in Ft Bragg, I and one of the instructors picked up 30 rounds found on the ground at one of the shooting points. These rounds had obviously been there for weeks (at a minimum) and were tarnished, and some were borderline corroded. We loaded and fired 27 of 30 rounds. Two rounds were bent and would not chamber, one was a dud.


So, what should be done?



1. Overhaul the gun every 5,000 rounds, or prior to any operational deployment. Use the existing and proven BHI Enhanced M4 SOPMOD Bolt Upgrade Kit (extractor/spring and Crane O-ring, extractor pin, gas rings) as well as a new buffer spring on rifles with more than 15,000 rounds on the original one.

The M4 SOPMOD Bolt Upgrade Kit is a proven refurbishing kit that will dramatically increase extraction reliability. The new extractor is of obvious benefit, the O-ring will give the extractor four times the tension, and the gas rings are necessary to trap enough gas to effectively propel the bolt carrier to the rear. Gas rings are prone to wear because of their repeated exposure to extreme pressure, heat and friction. (This friction is dramatically exacerbated when dust and sand are introduced via the operating environment.) The buffer spring (actually the action spring for all you nomenclature fascists) is often overlooked but is critical to absorbing the energy of the recoiling bolt carrier group and ensuring that it is propelled forward with enough energy to positively feed chamber and lock a live round even in a dry and dirty rifle. Worn out buffer springs often cause battering of the rifle, double feeds and failures to properly feed, chamber and lock. On my rifle, I use a Sprinco Super Duty M4 buffer spring as well as a DPMS Extra-Heavy Buffer (it is .2oz lighter than an H3 buffer). This combo makes my rifle super reliable and extremely soft shooting. (*The rifle must have a mil-spec gas port and a barrel of 14.5” or 16” with carbine gas system. On mid-length gas system guns, use the Sprinco standard CAR-15 spring. This spring and heavy buffer do not consistently work in Rock River Arms rifles, from my experience.)

2) Make it service/agency wide SOP that all magazines are marked in a numerical sequence with the operator’s initials/call sign/ battle number or some other individual marking traceable to him.

If both of these actions are taken there are two distinct benefits:
a. If the rifle malfunctions, the operator will be able to diagnose if it is magazine related and trace it to the unserviceable one. If unserviceable magazines are marked with red spray-paint on the bottom 1/3, they can be kept for training. This allows the operator to conserve operational magazines and get extra training on malfunctions as they could occur.
b. Properly marked magazines can always be returned to the original operator and if found on an objective will tell other elements who was there prior to their arrival.

*I prefer chrome silicon (CS) springs over stainless steel (SS) because they take minimal set. I am a big proponent of no-tilt followers, as well (Nearly all my magazines have MAGPUL Enhanced Self-Leveling “No-Tilt” Follower or CMMG Stainless Steel Anti-Tilt (SSAT) Follower. I refitted all my magazines in Iraq with CS springs and MAGPUL followers). I have used Colt, CMMG, MAGPUL and Lancer Systems magazines with great success. I am currently beginning a test on a new magazine and will be writing an article on magazine selection in general in the near future.

3) Keep a rifle log book with shot record and log of malfunctions per rifle.

4) Create a new training culture:

a. Teach carbine theory and true maintenance (this is covered in detail in my M16/M4 Handbook as well as Green Eyes and Black Rifles: Warriors Guide to the Combat Carbine by my friend Kyle Lamb of Viking Tactics).

b. Refine institutional maintenance so it is more responsive to the end user and overhaul guns yearly or prior to any operational deployments.

c. Malfunctions: Teach cycle of operations and diagnosis of mechanical failures (also in M16/M4 HB and Green Eyes).

d. Empower individuals to feel it is their sacred duty to make sure their rifles function properly.

e. Hold individual operators accountable for the performance of their weapons.

Piston-driven guns are all the rage now with the advent of 10.5” sub-carbine barrels. This is because a piston/op-rod gun omits the need to match the barrel to the gas tube length. That said, on standard 20” and 14.5” formats, direct gas guns are extremely reliable when properly cared for by both individual and institutional personnel. This takes more knowledge than effort, and it is owed to the men and women in the field.

Author's notes:

* This piece is written with the Soldier, Sailor, Airman and Marine in mind. If you are none of the above take what applies and disregard the rest. 90% is applicable to most that own or carry an AR-15/M16/M4/M4A1-series direct-gas gun in any capacity.

* I highly recommend both the M16/M4 Handbook and Green Eyes and Black Rifles: Warriors Guide to the Combat Carbine as technical training references for all serious shooters.

*I receive no money from Sprinco, but choose to use their products exclusively because they have worked extremely well under extreme use. All 15,000 rounds were fired on the same extractor spring.

*Any time you change any part, i.e. buffer spring, buffer weight, magazine followers and springs, etc., test fire the rifle before operational use!

Editor's Note: The photos accompanying this article were provided by the author (Mike Pannone), and are copyrighted.  The M4/M4A1-type carbine pictured is semi-auto-only, and is the back-up weapon to the actual weapon the author used for the high-round-count test covered in this article. The pictured weapon is identical, except that the free-float (FF) Mil-Std-1913 "Picatinny" rail system/forend rail tube on it is 2" shorter than the one on the actual weapon used. All else, i.e. springs, weights, etc., are the same.

About the Author: Michael Pannone a.k.a Mike Pannone is currently a Senior instructor for both Team VTAC (Viking Tactics) and Mid-Atlantic Training Resources (MATR), and a certified Colt Armorer. He is also a former operational member of U.S. Marine Force Reconnaissance, U.S. Army Special Forces, and specially selected elements of the Joint Special Operations Command. He has participated in stabilization, combat, and high risk protection operations in support of U.S. policies throughout the word as both an active duty military member, and a civilian contractor. During his military career, Mr. Pannone was the Distinguished Honor Graduate of a Level 1 SOTIC held at Ft Bragg. He currently instructs U.S. military, law enforcement (LE), and private citizens around the country as an adjunct instructor with several different organizations. He can be contacted via e-mail at ctts at live dot com.

Company Contact Info:

Colt Defense LLC
547 New Park Ave
West Hartford, CT, 06110
800-241-2485 Toll Free
860-232-4489 Office
860-244-1442 Fax Website

Viking Tactics, Inc. (VTAC)
Fayetteville, NC 28306
OFFICE: 910-987-5983
INSTRUCTION: 360-790-5743
FAX: 910-425-0700

Noveske Rifleworks LLC
P.O. Box 1401
Grants Pass, Oregon 97528
Phone: 541-479-6117
Fax: 541-479-2555
Orders Email:

Blackheart International, L.L.C.
RR3 Box 115
Philippi, WV 26416
877-244-8166 Toll Free
304-457-1280 Office
304-457-1281 Fax Email Website

Sprinco USA
7804 Danz Blvd.
Austin, TX 78724
Orders: 1-800-397-9530
General Inquiries: 512-331-8797
Fax: 512-331-9172
Email: Main Website Tactical Springs Website

Tactical Springs LLC
7804 Danz Blvd.
Austin, TX 78724
Telephones: Local: 512-926-3100
Toll Free: 866-515-2715
Fax: 512-331-9172 Website

DPMS Firearms, LLC
3312 12th Street SE
St. Cloud, MN 56304
Phone: 320-258-4448
Fax: 320-258-4449
Toll-Free: 800-578-3767


Magpul Industries Corp
400 Young Court, Unit 1
Erie, Colorado 80516-8440
Toll-Free: 877-4MAGPUL (877-462-4785)
Office: 303-828-3460
Fax: 303-828-3469

Military Cage Code 1LX50

CMMG, Inc.
620 County Rd 118
Fayette, MO 65248
Phone: 1-660-248-2293
Fax: 1-660-248-2290
Sales Email:

Lancer Systems
7566 Morris Court,Suite 300
Allentown, PA 18106
610-973-2600 Office
610-973-2601 Fax Email Info Email Sales Website

Erik Lawrence, Owner
Mid-Atlantic Training Resources, LLC (MATR)
112 N. Wood St.
Philippi, WV 26416
Phone: 304-457-1280
Fax: 304-457-1281

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About David Crane

David Crane started publishing online in 2001. Since that time, governments, military organizations, Special Operators (i.e. professional trigger pullers), agencies, and civilian tactical shooters the world over have come to depend on Defense Review as the authoritative source of news and information on "the latest and greatest" in the field of military defense and tactical technology and hardware, including tactical firearms, ammunition, equipment, gear, and training.

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