A Simple Primer on the AR-15 Rifle

The M16A1, M16A2, M4A1 MWS, and M16A4 MWS rifles, the primary workhorses of the United States Armed Forces since the 1960s. They all draw their lineage straight back to the AR-10 of the early 1950s.

The AR-15. Armalite Rifle, Design 15, designed in 1957 to be fielded as a lightweight rifle for US Air Force security forces, has become one of the most prolific and misunderstood rifles in the modern world. Love it or hate it, the AR-15 is definitely here to stay. Itself a scaled down version of the AR-10, the AR-15 is, in its original guise, an extremely lightweight, handy, portable, accurate rifle which is capable of accuracy far beyond what many think possible out of it, and it is typically chambered for a lightweight cartridge with little recoil that is more than capable of doing a vast number of tasks when employed correctly by competent shooters.

An original AR-10. Certainly unique in appearance.

Designed by Eugene Stoner, Jim Sullivan, and Bob Fremont in the early 1950s, the original AR-10 was adopted by a small handful of countries. It certainly had a unique appearance, and quite a lot of interesting features. Here you can see a very old commercial showing an AR-10 and when you compare it against much of the competition of its period (the FN FAL, the H&K G3, and what would later become the US M14), you can definitely see why it may raise a few eyebrows and pique some interest.

The original AR-15 design was scaled down from a larger AR-10, and you can see much of that lineage in this photo here. 

It was later scaled down to handle the 5.56 cartridge, which it would stay in for the majority of its development since then. It was introduced with US forces in the Vietnam War of the 1960s, and many of the issues it would see would go on to haunt it to this day. I shared an article about that very topic, which you can read here.


The Colt Model 601, fielded by the Air Force during the Vietnam War, is certainly much more akin to the modern AR variants than the earlier AR-10/AR-15.

From the introduction of the Colt 601 with the Air Force and subsequent rapid development cycle that would result in the M16A1 rifle, the M16 has seen quite a lot of developments and derivations. From it, the HK416/417 weapons were developed, as well as the Canadian C7/C8/IUR rifles. Many other countries have adopted various systems based on the rifle using an external piston, and still more have been designed and developed for the civilian market. Along side the AK, it is one of the most prolific weapons in the world.


Cycle of Operations

The genius of the AR-15 rifle is three-fold:  Its lightweight construction makes it very easy to carry, its inline recoil system makes it incredibly controllable, both in semi-automatic and full automatic fire, and its hybrid direct impingement/internal piston operating mechanism creates few moving parts in the system, and centralized them in one place, simplifying and stabilizing the weapon during firing.

If you’d like to see a video demonstrating the cycle of operations, you can watch this original training film, which explains it beautifully.

Otherwise, I will give a much simplified explanation here. Prepare yourself for…..

The Simplest Explanation of How ARs Work You’ll Ever Read

  1. The bolt being in the closed and locked state, the trigger is squeezed.
  2. The hammer falls and strikes the firing pin
  3. Expanding gas from the firing cartridge is redirected through the gas port and tube in to the gas key of the bolt carrier, which guides it in to an expansion chamber inside the bolt carrier group
  4. The gas expands, pushing against the bolt and forcing it to unlock and move rearward under recoil and residual pressure
  5. The bolt moves to the rear, extracting and ejecting the spent case
  6. The rearward action of the bolt carrier pushes the hammer back until the disconnector grabs the back of the hammer, preventing it from falling again
  7. The buffer and buffer spring push the bolt carrier back forward, picking up a fresh round from the magazine
  8. The bolt finishes its forward stroke and rotates in to battery, ready for the next shot
  9. The shooter releases the trigger until the disconnector releases the hammer and it moves on to the sear, ready for the next shot.



I hope this has been enlightening, and helped giving you an idea of where the modern AR-15 came from and how it functions. All photos either came from Wikipedia or were in the public domain. If you have any questions or concerns, or you wish to be credited for a specific photo, please email the webmaster through the Contact Us page.

~ The Pennsylvania Rifleman


Rumors of my Assimilation are Greatly Exaggerated

So… I’ve been away for a while. Sadly, life got in the way pretty crazily and I have had no time or energy to write or even really get out to the range most of the past spring and summer, and for the tail end of winter. Paired with crazy bad writer’s block, I simply have not put out content in somewhere around 8 months, I think. I hope to see that come to an end, now, but I won’t be holding myself to any sort of publication schedule for the time being. I will get out what I can, when I can. No later, no sooner. It is incredibly important to me that I am producing quality content, and it’s more important that I do that than try to meet some arbitrary production schedule. Please stay tuned for more on basic rifle marksmanship, to start with, and hopefully some more content to go after that!

~ The Pennsylvania Rifleman

BRM – The Fundamentals of Marksmanship

All shooting ends up boiling down to application of the fundamentals. Whether it’s a two mile shot on a 12″ steel plate, shooting a 12-point buck at 300 yards, stopping a car-bomb with a .50 BMG rifle, or fast-paced CQB shooting, the fundamental basics of hitting what you’re shooting at are largely the same. They even apply with weapons like machine guns and grenade launchers! So it’s pretty important to have a strong understanding of the basic fundamentals and be able to exercise them. You can never be too accurate!

The Fundamentals

So let’s break down the five fundamentals of a good shot. What are they?

  • Steady Position
  • Aiming
  • Breath Control
  • Trigger Squeeze
  • Follow Through

Each of these have multiple points that go in to them all, and we’ll be going in to each part individually, but the point of this article is to give a rough overview of what everything is and how it contributes to an accurate shot. Let’s start with “Steady Position”.

Steady Position – 


A steady position is the bedrock upon which everything else lays. If you have a rock solid position, then everything else should quickly and easily fall in to place. More than anything else, your position will effect your marksmanship shot-to-shot, as it is something that you assume at the beginning of your shooting and tend to hold through the string of fire. You can correct all of your fundamentals from shot to shot pretty easily, but your body position is the hardest to change over time. The hallmark of a good, steady position is that you can squeeze the trigger and hold the front sight steady all the way through the hammer falling. Ultimately, the best judge of position will be you. If it is uncomfortable, you are probably positioned wrong. It is good to start with a few guidelines and then sort of settle in to the perfect position for your biomechanics. With time, and dry fire, you will get very good at quickly and efficiently assuming a rock solid position no matter what you’re doing.

When you can do it quickly and efficiently on a square range, try it out with some irregular terrain. Try to quickly assume a good kneeling position behind some cover. You may find that the traditional positions used for marksmanship don’t work so well on their own. When that happens, use the basic concepts that make that position a good one to create your own shooting positions in the field. We will cover this more a little later when we talk about “field shooting”.

Aiming – 

Aiming is primarily two things:  sight alignment and sight picture. These sound quite similar, and they are, but the can cause incredibly different problems, so it is important to tackle them as separate things. Diving deep in to them is somewhat outside the scope of this article, but I at least want to describe what they are and the difference between them.

Sight alignment describes the relationship between the front sight and the rear sight. When shooting with optics this is changed somewhat. Sight alignment with optical sights tends to refer to ensuring the reticle is centered in the field of view, and that you aren’t too close or too far away, occluding the sight.

Correct sight alignment on an M16-series rifle.

A sight picture, would be a sort of “big picture” idea of the sight, referring to the relationship between the shooter’s eye, the rear sight, the front sight, and the target. The target should appear fuzzy and the front sight should appear crystal clear. With optics, sight picture refers to the reticle being centered on the target, and the target should appear crystal clear. The primary benefit to optics over iron sights, when talking about sight picture, is that optics reduce the number of planes being focused between, thus making it easier to shoot quickly, and with more ability to react to change.

Breathing (and Heart rate) – 

I won’t take too long to talk about how breathing and heart rate effect shooting. Simply put, your heart beating and your chest rising and falling through a breath effect the sight picture. The best time to break the shot is during a natural respiratory pause, either after breathing in, or after breathing out. The best time, in the author’s opinion, is after breathing out, but the important thing is to be consistent. Whether you break the shot while breathed in or out is not super important, just that you do it the same way every time.

The primary effect of heart rate is that your heart can use up the available oxygenated blood quicker, forcing you to breathe at a faster rate. The best way to combat this is to focus on breathing at a comfortable cadence, and simply control yourself through the entire breathing process. With time, this will become automatic.

Trigger Squeeze – 

One of the biggest mistakes I see people make is on their trigger squeeze. It is incredibly important to smoothly press the trigger straight back, and not jerk it around or move it side to side. Jerking the trigger is something I see a lot of young shooters and shotgunners-turned-rifleman do, as shotgun shooting tends to be more forgiving of poor marksmanship fundamentals, so long as your aim is good. It is extremely important to focus on smoothly pressing the trigger straight back.

Follow Through – 

Follow through is one of those things that always seems extremely dubious as to what it means. The easiest way to describe it is that after the shot breaks, it is extremely important that you hold your sight picture all the way through, as a sudden jerk after breaking the shot can cause a miss. It is also quite helpful in allowing you to see where your bullet struck so you can make shot corrections.

Conclusion – 

All of these fundamentals will be focused on in their own articles, as there is quite a lot going on in them and it is very important to break it all down to a granular level to assist in making good, accurate shots. There is no such thing as advanced shooting, only advanced application of the fundamentals. Master these, and you can shoot almost anything.


The Pennsylvania Rifleman

The Real Story of the M16 in Vietnam

The original M16 was first fielded in Vietnam in the 1960s, and there it received a very bad reputation. One which was unfairly deserved. There are a lot of stories given about how it failed, why it failed, and why multiple changes were made to the design early on. However, Chris Bartocci (author of Black Rifle II and one of the most knowledgeable people on the AR-pattern rifle) has an awesome video on YouTube where he describes what actually happened, the real story, with the M16-family’s development. I recently watched the video and wanted to share it with my readers, as a look at the real history of the rifle’s development is useful in dispelling modern myths and misconceptions, as well as helping to direct modern development to the rifle.


The video can be seen here.

*Disclaimer: I am just a viewer of Chris Bartocci’s content, and receive no monetary compensation for sharing of his video.

~ The Pennsylvania Rifleman

*Editor’s Note – YouTube took down Chris’s original channel, and so the link on this page has been broken. They have re-started on YouTube under his company’s name, and re-uploaded the video, so I have fixed the link to have the correct URL. Please enjoy, and let Chris know you came from the Pennsylvania Rifleman blog!

When is the next BRM Post coming?

Hey all, a quick note from The Pennsylvania Rifleman –

Over the past three weeks I have written the upcoming post on the Fundamentals of Marksmanship about three times now, and every time I have written it over again, it comes out reading like a technical manual. I don’t know about you, but I don’t find those very exciting, and my goal is certainly not to bore you, my illustrious reader. So please bare with me for another week or two while I finish writing it.

Thanks for your understanding!

~ The Pennsylvania Rifleman

Fieldcraft! What is it?

So, I mentioned earlier that as a part of this blog we will be discussing fieldcraft which relates to practical riflery. But what exactly is fieldcraft?

Fieldcraft is decidedly different from bushcraft or survivalcraft, which you might initially think it is. Simply put, fieldcraft is a set of techniques involved in living, traveling, or making military or scientific observations in the field, particularly while remaining undetected.

Fieldcraft certainly shares skills with bushcraft and survivalcraft, but many of its skills are quite different, and it has a different end goal. Fieldcraft is useful to many outside of the military, as well, and while it is of little use to the competitive shooter or weekend plinker, to those of us spending time afield with a rifle it is of great importance. We will be exploring a good bit of field craft which is useful specifically to a rifleman, and dip somewhat in to other fieldcraft skills later, over the course of this blog, but I felt that a brief introduction to what fieldcraft is would be a useful way to start out with.

I hope you, my reader, are willing to stick around for more!

~ The Pennsylvania Rifleman

A Sexy Romanian Lady – The Romanian M1969 Training Rifle

The Romanian M1969 Training Rifle, an extremely accurate .22 rimfire rifle.

While I finish writing the post on the fundamentals of marksmanship, which will be coming in a couple of weeks, I thought a brief teaser of the Romanian IMC2 trainer that we will be using when January rolls around for some practice might be nice. She sure is a beautiful rifle.

The barrel shank has most of the identifying markings

This particular example was made in 1978, and is serial number S-3842 and is a non-matching example. The Romanian IMC2, also known as the M1969 training rifle, is a bolt action .22 rimfire rifle with a 5 round single stack detachable magazine. The magazine in this one is pretty loose, and has to be held in place when feeding the last few rounds to ensure proper feeding.

The iron sights are very clean and accurate

The sights flip up and range from a 25m notch to a 100m notch, with a 50m notch leaf in between the two. The sights on this example are dead on and it is extremely accurate. The sling and AK-style buttstock cleaning kit are both original Romanian issue, but I do not have an original cleaning rod for it. There is no provision to place it on the rifle, sadly.

This thing has a ton of really interesting markings!
The action is simple and robust, always a good feature in a rifle

I hope you enjoyed this brief teaser at my Romanian IMC2. When January rolls around and I am able to get out to the range, I will hopefully be doing some shooting with this rifle and will be doing a full review on it, as well as discussing the use of rimfire rifles as training tools.

~ The Pennsylvania Rifleman

Intro to Basic Rifle Marksmanship

A soldier firing his rifle from the kneeling supported position – FM 3-22.9

The ability to hit any target that you can see is a powerful one. Under absolutely perfect conditions, (an unobstructed plain), your naked eye can see another human being up to 3 miles away. Of course, you would not be able to identify them, and anyone making any attempt to hide from being seen would complicate things, but it is theoretically possible.

Naturally, when discussing practical riflery we aren’t talking about targets at that degree of extreme range. For our purposes, when we talk about practical riflery, we are referring to the use of rifles in field conditions to engage targets ranging in size from varmints like coyotes up to large game and two-legged critters at any range with which you can hit the target and have an effect upon it, though not necessarily with the same rifle.

To be able to do this, we need to understand basic rifle marksmanship. My hope with this blog has always been to learn alongside my reader, so as I write this coming series on Basic Rifle Marksmanship, I will be learning these concepts as well. I hope that this series is helpful to new shooters and experienced shooters alike.

~ The Pennsylvania Rifleman

Lt. Col. Dave Lutz on the M16A2

Something great actually appeared over on Arfcom for once. It started with an innocuous question – Why did the military go from the A1 to the A2 pistol grip?

It’s not often that you ask a question and someone comes along to say “Oh yes, that was me”. Lo and behold, the man himself USMC Lt. Col. Dave Lutz (username “Coldblue”), who had a big part in the development of the M16A2 product improvement program, came along and answered all manner of questions on the changes in the M16A2 program, from the sights, the stock, the grip, the barrel, and loads of other awesome things.

It really is a treasure trove of historical and practical interest discussing the technicalities of why the changes were made and how it happened.

~ The Pennsylvania Rifleman