M16 vs M4

Which Duty AR is King? – Nick Perna, a former soldier and currently a cop, weighs in on whether the M16A2 or M4 is a better overall weapon system.

Age equals experience. One of the few perks of getting old is that you get exposed to more things throughout the course of your life. This includes weapon systems. I’ve been making a living with a firearm since the late 1980s.
In jobs ranging from the military, bounty hunting and law enforcement, I’ve carried a wide variety of handguns, long guns, crew-served weapons and other things that go “Bang!” I’ve personally bore witness to the development of the M16/M4 weapon system throughout my adult life.
My first experience was with the M16A1. I carried the triangle-gripped Vietnam-era weapon in the 1990s as an ROTC cadet and later as a member of the National Guard in Florida and California. It was full-auto, which was nice. The fore grips were a little flimsy and could bite at one’s hands at times. The rear sight was somewhat unsophisticated compared to later models, but it worked fairly well.
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Later, while on active duty with the 82nd Airborne, I was issued an M16A2. I had longed to carry one since I had seen pictures of paratroopers in Panama carrying them during Operation Just Cause in 1989. Compared to the M16A1 it seemed state of the art. Overall, the weapon was better built. A heavier barrel was used, increasing accuracy and durability.
The triangle foregrips were replaced with more stout, ribbed ones. The rear sight was replaced with one that could be manipulated with your hand (the M16A1 required the tip of a bullet to be inserted into a detent to adjust it). The one thing the military did that didn’t make sense was replacing the full-auto option on the M16A2 with three-shot burst. From the time of the introduction of bolt-action rifles in combat, generals have been obsessed with ensuring that soldiers don’t waste ammo. Some magazine-fed, bolt-action military rifles in World War I were equipped with a device that allowed loading only one round at a time, leaving the rounds in the magazine for emergency situations.

Fast forward to the latter half of the 20th Century and military leaders, fearing massive ammo waste through “spray and pray” tactics, did away with full-auto for America’s military rifle! When it comes to senior officers making micro-decisions that negatively affect soldiers, little has changed throughout the years.
I carried the M203 variant of the M16A2. This is hands down my favorite version of this weapon system; 5.56 up top, 40mm on the bottom, what else can you ask for? The 40mm can launch explosives, flares, flechette rounds and more. I took pride in the fact that I was, at the time, the highest-ranking grenadier in the 82nd Airborne! To my knowledge no other officers were carrying the 203 at the time. It made for a lot of strange looks on range day when the “lieutenant” showed up.

I’ve carried the M4 variant in the military and as a SWAT officer. It’s a great system. The shorter length makes it ideal for close-quarters battle. Getting rid of the carrying handle and replacing it with an ample Picatinny rail makes sense in the modern era where optics are standard-issue. Bringing back full-auto was a good move as well.

SO, WHICH ONE is the best overall weapon system? Is the M4 the king by virtue of the fact that it is the most current variant? It depends on what you are looking for and what criteria are used to judge.
In this comparison I’m going to exclude my personal fave, the M203. It’s a unique weapon and all modern M16/M4 variants can be turned into a 5.56/40mm combo so, in essence, it’s in a category all its own.
The M4’s major advantages are size and modularity. It is significantly shorter than an M16A2, giving it a lot of advantages. It’s better for carrying in confined spaces such as inside a vehicle and aircraft. It is also more user-friendly when clearing buildings, which is a major component of what the military and law enforcement do.

This size comes at a cost, though. The Achilles heel of the M4 is the retractable stock. The buffer tube that supports the stock is the weakest part of the weapon. The buffer tube can be bent, dented or damaged in some other way through hard use. This can be catastrophic because a damaged buffer tube won’t allow the buffer spring and bolt carrier group to travel down it when the weapon is cycling a new round. If it’s damaged enough that the bolt carrier group can’t fit in it at all, then a round can’t even be chambered. The M16A2’s buffer tube is encased in a hardened, high-impact plastic stock.
This does a good job of protecting it. MOUT (Military Operations in Urban Terrain) manuals used by the military recommend using the M16A2 as a platform for a soldier to stand on to enter a window! In other words, two soldiers hold the M16A2, one holding the barrel, the other the stock. A third soldier then steps onto the rifle while his partners hoist him into the window. That’s a pretty robust weapon! As a sidebar, I don’t recommend trying this at home. If you absolutely can’t resist doing so, A) make sure the weapon is unloaded, and B) borrow someone else’s rifle when you try it. Another limited application for the M16A2’s stock is using it as an impact weapon. As part of bayonet training, many soldiers have been taught to use the stock to butt-stroke opponents. Try that with an M4.
The other issue with the M4’s size is barrel length. A standard-issue M4 has a 14.5-inch barrel. This translates to an effective firing range of 500 meters. The M16A2 has a 20-inch barrel with a firing range of 600 meters. This means greater hit probability at longer ranges. In the recent conflicts in Afghanistan and Iraq, long-distance engagements have been the norm, so every meter matters.
Being the more modern weapon, the M4 is more modular. With rails on the receiver and foregrips, you can hang just about every device imaginable on one – scopes, holographic sights, back-up iron sights, lights, lasers, foregrips, can openers, potato peelers, you name it. The butt stock is easily replaceable too, although it still ends up on the same subpar buffer tube. The M4 is the most adaptable weapons platform on the planet, period.
IN ITS MOST PURE FORM the M16A2 is pretty much a “what you see is what you get” weapon. It predates much of the add-on gear available to AR enthusiasts today. There is limited mounting options for optics on top of the carrying handle, and the offset (distance between the point of aim of the optic and the potential point of impact from a round leaving the barrel) is pretty significant.

This becomes a problem at close-range, CQB distances. The single-point mount on a carrying handle – basically a hole in the top of the handle where you use a single bolt to lock down an optic – is also a lot less stable than a Picatinny rail with multiple points of contact. However, if you want the best of both worlds, look to the United States Marine Corps for a solution. Enter the M16A4! It has all of the positive attributes of an M16A2, such as a longer barrel and fixed stock. At the same time, it has a Picatinny rail in place of a carrying handle and rail-equipped foregrips just like the M4. As an Army vet it pains me to say this, but the Marines have done a better job in recent times of fielding better weapons and equipment to meet the needs of their troops. While the Army was struggling with finding a camo pattern that worked (remember the ACU, Army Combat Uniform?) the Marines had the excellent MARPAT pattern. The M16A4 is just another example of USMC ingenuity. So which weapon you choose really depends on what your needs are. The M4 is the highly adaptable king that is the premier CQB rifle. The M16A2 is the more robust weapon that can reach out and touch targets at longer distances. Pick the one that better suits your needs. Or, better yet, buy both. Editor’s note: Nick Perna is a sergeant with the Redwood City Police Department in northern California. He has spent much of his career as a gang and narcotics investigator. Perna previously served as a paratrooper in the US Army and is a veteran of Operation Iraqi Freedom. He has a master’s degree from the University of San Francisco.

Here’s a different perceptive from Youtuber James Reeves from TFB.TV