American Gunsmithing Institute
By Mark Foster, Master Gunsmith
Law Enforcement Officer Armorer
Instructor for the American Gunsmithing Institute
The AR-15 is a versatile semi-automatic rifle platform that can be configured to be very effective for a number of different purposes, from personal protection, law enforcement duty, target competition, hunting small and medium sized game, as well as for just having fun. The AR-15 platform has the unique ability to accept different caliber barrels or complete upper receivers and a myriad of add-on components to configure it to a wide variety of purposes. Most people know that the M-16 platform has been around for over 55 years. However, in the last few years, the AR-15 civilian sporting version has dramatically increased in popularity and the number of components available have gone ballistic.
I recently completed a video with the American Gunsmithing Institute (AGI #346DVD), AR-15: Practical, Tactical, or Tacti-Cool, which looks at many of the current components that can turn your AR-15 into a rifle that best suits your needs or wants. There are many great companies making quality rifles and even more companies making great add-on components to upgrade those rifles. Some components are very practical and enhance the rifle platform with minimal cost or work. Some components are more “Tactical,” meaning they assist in a specific mission or purpose, whatever that may be for you. Some components are “Tacti-cool”, meaning they don’t necessarily help with a real need… but they enhance the look and you “just gotta have it.”
You can take any AR-15 rifle and reconfigure it yourself to fit whatever purpose or desire you have. In my video, we take a look at many components, add-ons, optics, and tools. We discuss gas impingement vs. gas piston systems, along with the pros and cons of each. Let’s take a look at just a few of the components that I think are the most practical enhancements to a rifle.
Other than the fit of the upper and lower receiver, barrels and trigger groups are, in my opinion, the most important components for an accurate rifle. After that, handguards or fore-ends and optics are the most practical or tactical upgrades to any rifle.
If you are only using your rifle for close distances or for plinking, don’t spend a lot of money on a barrel. Currently, inexpensive barrels are in the $100-$150 range and are usually not chrome lined. Chrome lining prevents corrosion and aids in cleaning – nice to have but not necessary if you clean and lube your rifle properly. If you are one of the lucky group that shoots full-auto for fun or you shoot at close range, why spend a lot of money for an expensive barrel? Spend your money appropriately to get the best “bang for your buck.”
If you are shooting long distance, participating in competition matches or any other precision shooting and need sub-“Minute of Angle” accuracy, don’t buy a cheap barrel and expect to be in the winner’s circle. For the best accuracy, go with top of the line barrels from Krieger, Hart, or Shilen but expect to pay $600 plus for the barrel. These barrels, when properly installed, will give you the best chance at superior accuracy.
For barrels that offer MOA accuracy or better, expect to pay in the $250 – $500 range. Barrels from Noveske, Criterion, Wilson Arms, Wilson Combat, Spike’s Tactical, Daniel Defense, and others are very good barrels capable of MOA groups or better. These barrels are practical upgrades that can give you the potential for better accuracy in hunting rifles, law enforcement dedicated marksman rifles, or any other purpose that requires above average accuracy.
If you are only going to change out a barrel on rare occasions, have a competent gunsmith do it for you. If on the other hand, you will be doing it often and are willing to buy the proper tools, you can learn to do it yourself. In the AGI video AR-15: Practical, Tactical, or Tacti-Cool, I show a barrel change and installation of a free-floating handguard using two different methods, along with the tools needed for a proper barrel change. The torque settings and checking headspace of the bolt are critical steps in the process but that does not mean that only a gunsmith can do it. If you have the proper tools, headspace gauges, and an understanding of the process, just about anyone with mechanical aptitude can do it. You can also get the AGI video on building the AR-15 rifle (#323DVD) and go through the procedure even more in depth. (ED NOTE: This video is also part of a set here.)
Standard military trigger groups are practical but not necessarily great. Heavy and creepy trigger pulls are common and resets are usually longer than we might like. They work for general purposes but won’t get you into the winner’s circle of a competition unless they are re-worked. If you want to use your existing hammer / trigger but want to improve it, AGI has a video on trigger jobs for the standard trigger (AGI #335DVD). With the proper tools and procedures, you can eliminate the heavy, creepy standard trigger pull. This is an advanced technique best left to a gunsmith, so if you want a better trigger pull that doesn’t require as much skill, look into two-stage or drop-in triggers. (ED NOTE: There is also a combination deal on all the trigger courses here.)
Two-stage triggers are more expensive than standard triggers but usually deliver a lighter and crisper trigger pull. Great for competition, hunting, law enforcement dedicated marksman rifles, or just to have a better trigger on any rifle. Rock River Arms make a good two-stage trigger but you can expect to pay $125 uninstalled. Geissele Automatics makes, in my opinion, the best two-stage triggers, but they cost $175 or more depending on the model. I have both Rock River Arms and Geissele two-stage triggers and prefer this style on most of my rifles, including law enforcement patrol rifles and hunting rifles. They are practical and tactical rolled into one: a better trigger pull to give you the best chance at accuracy.
Drop-in triggers can be a great way to go because they are easy to install and come in tactical and competition styles. I like Wilson Combat and Chip McCormick drop-in triggers. I’ve used the Wilson Combat TTU trigger in a dedicated marksman rifle with great success. Be careful of a drop-in, or any other trigger group, that has adjustment screws that can back out and prevent the weapon from firing. Not a big deal on the range but it can be a real problem in a law enforcement or personal protection situation when your life is on the line.
Triggers and hammers are fairly easy to replace, especially with the drop-in type. The pins are the same for the hammer and trigger, so they are interchangeable. Be mindful of the direction of the hammer and trigger springs before you remove the pins – they need to go back in the same positions. The hammer spring is formed with a closed “U” on one end and two legs on the other end, with a coil in the middle of each leg. When installed on the hammer, the “U” will be at the top rear of the hammer and the coils will face to the rear. This will allow the coils to get tighter when the hammer is cocked. A major cause of light strikes is putting the hammer spring on backwards, which allows the coils to loosen when the hammer is cocked.
I have a simple way to remember how the hammer spring goes on a hammer. If you look at the spring from the side, you’ll see that the “U” and legs form a line on one side of the coil. If you are right handed, take the spring and hold it in your right hand with the coils to your left. Put your left pointer finger between the two coils, with the closed “U” end up and the legs down. The line of the “U” and legs should be facing the tip of your finger. Now take the hammer in your right hand, with the striking face to the right and the pin hole down. Move the hammer to the tip of your left finger and slip the coils onto each side of the hammer bosses (where the hammer pin hole is located). The “U” will be against the back of the hammer and the legs will extend down and slightly forward. If you are left handed, simply do a “mirror reverse” of the above. This method is used by assemblers at Rock River Arms and it is very quick and easy once you try it.
With the lower receiver separated from the upper receiver, use a 1/8” punch and simply push out the pins. If the pins are difficult to push out, a small plastic hammer can be used to assist. Push out the hammer pin first and the hammer will spring up and out of the receiver. Then remove the trigger pin and remove the disconnector and trigger. The safety selector must be on “Fire” and you may have to tip and wiggle the trigger to pull it out. The disconnector spring usually does not come out of the trigger. The disconnector spring has a flared end that goes into its hole in the trigger and “locks” into place. Bolt catch springs are very similar in size to the disconnector spring but do not have a flared end – be aware of this difference if you have both laying on your bench.
Replace the hammer and trigger in the reverse order but be aware of the spring positions and the disconnector. Place the trigger back into the receiver and drop in the disconnector with the “hook” facing forward. The trigger spring legs should be facing forward and the closed “U” portion should be under the front of the trigger. Carefully align the holes in the receiver with the holes in the trigger and insert the pin. A 1/8” punch can assist with aligning the holes so the pins can be started easier. A hammer is not usually necessary and never attempt to pound the pins in place or damage can occur to the receiver. After replacing the pin, check the trigger to make sure the spring tensions it forward.
When installing the hammer, make sure the two legs of the spring go on top of the trigger pin. This does two things – first it gives the correct amount of spring tension to assure a proper hammer strike, second, there is a groove on the side of the hammer/trigger pins, The spring leg helps prevent the pin from coming out of the receiver. As with the trigger, using a punch will assist with aligning the holes in the hammer and receiver. Most pins will push in with moderate force and a hammer is not usually necessary but can be used with caution.
If you use a two-stage trigger, such as a Geissele, the set will come with hardened pins – use only the pins that come with the set. Install the trigger first, with the trigger spring legs facing forward. Do not use a hammer to beat the pins into place, you can damage the receiver – push the pins into place after aligning the holes. Install the hammer with the legs of the spring resting on top of the trigger pin, align the holes and push in the pins. Test the trigger group and safety to make sure the safety prevents the hammer from falling.
The drop-in triggers are generally as simple as they sound. Remove the old hammer / trigger and replace with the self-contained drop-in hammer / trigger, replace with the new pins and test function the safety.
If you have never replaced an AR trigger/hammer, AGI has a video on the AR-15 (#103DVD) that shows the complete disassembly / reassembly and functioning of the rifle platform.
There are lots of choices in handguards and stocks. I think that they can be generally segregated into six basic styles – standard, standard free-floating, full quad-rail, full quad-rail free-floating, round free-floating, and combination round/rail free-floating. There is no “best” handguard, but there are better choices depending on the purpose of the rifle.
The standard military style triangle or round plastic types are very practical. They will work adequately for almost all purposes. If you have a basic military or law enforcement, home defense, plinking, or any other general-purpose rifle, the standard handguards will work just fine. I prefer Magpul MOE handguards as an upgrade to the practical and tactical rifle. They feel better and have options for light rails. The Magpul handguards are a little more difficult to install because they have a top and bottom piece and the bottom needs to be “rocked” into place. Not really difficult but it takes a little more practice than the standard handguards. Brownell’s sells handguard removal/assembly tools that use leverage to make the job easier for any handguard that uses the standard “Delta ring” system.
Full quad-rail handguards are everywhere and made by dozens of companies. I consider them more in the tactical category, better suited to law enforcement and military CQB. Why? Although they have the capability to add on lights, lasers, sights, etc., they are generally heavier than the standard plastic and can have sharp edges that are best suited to gloved hands.
Surefire makes non free-floating full quad-rail handguards that use the standard Delta ring system. Daniel Defense, Yankee Hill Machine, and others make free-floating full quad-rail handguards. The free-floating types use special barrel nuts that will require that you disassemble the barrel. Free-floating handguards may aid in accuracy but require more skill and tools to install. In AR-15: Practical, Tactical, or Tacti-Cool, I show how to replace a standard handguard with a free-floating type, including the tools needed to do the job properly, and they are not that expensive.
You may wear gloves while hunting, but if you want something more practical for that purpose, I prefer the combination round/rail handguards, such as the Yankee Hill Machine Jarrett series. I prefer this type or the round free-floating type for hunting.
There are aluminum or carbon fiber handguards that offer round, round with quad-rail sections, or have rails that mount anywhere they are needed. These types are great for varmint or 3-gun competition rifles. The Troy Industries Alpha Rail or Geissele Automatics are great choices for 3-gun competition rifles.
Buttstocks come in fixed length, collapsible, skeleton, and adjustable – any style to fit you and your needs. Fixed stocks are generally more practical for hunting and most competition shooting, collapsible are better suited to law enforcement, military, or home protection.
The great thing about the myriad of handguards and buttstocks available is that you can make the rifle suit your needs. It is highly probable someone at your local range already has one and you can ask to try it to see how it feels before you spend your money. In the video, I show lots of examples of different styles of handguards and buttstocks to help you decide which is right for you.
Sights and optics:
The standard A-2 style sights on most modern rifles work well – in the hands of a good marksman, they are capable of accuracy to 600 yards or more. For us mortals, optics are probably a better choice. I suggest getting a reflex sight that is military grade, it will generally hold up better to harsh conditions. I consider reflex sights to be very practical – easy target acquisition and, since you can keep both eyes open, better overall vision of what’s going on around you. I have used EOTech and Aimpoint sights on law enforcement and personal rifles for over 10 years. I prefer Aimpoint optics because of their durability and have the T-1 micro sight on my personal and Patrol rifles. The new Aimpoint PRO is another great choice and has the ability to stay continually on for more than a year before the battery needs replacement.
For magnification, your budget is the deciding factor. There are decent scopes for $200-$300 but high quality glass is expensive, with some scopes going over the $3000 mark. Get the best you can afford that meets your needs. Besides LE and military types, many experienced hunters think nothing of spending more on high quality glass than their rifles. The rationale is if you can’t see your target clearly under all reasonable circumstances and have full confidence that the sight will continue to survive and perform in the harshest environments, it doesn’t make much difference how good your rifle/cartridge platform is.
If you need back-up iron sights, there are lots of great choices. Aluminum, steel, and polymer sights are available and can be fixed or flip-up style. The SWAT team at my department has tested the Magpul MBUS polymer sights for over a year and they have not had any malfunctions or loss of zero. Very practical and tactical!
If you are into 3-gun competition and can’t have multiple optics, there are 45-degree offset iron sights available. I’ve tested the Dueck Defense offset sights – they are durable and allow a quick transition from optics to iron sights. Get them if you really need this type of auxiliary sight for competition but I think they are more in the “Tacti-Cool” category because of the limited need for this type of sight system.
What are the best components to put on your rifle? That really depends on the end use of your rifle. To make a general-purpose rifle better while still being practical, I like Magpul MOE handguards, a Magpul ACS-L collapsible stock or MOE rifle stock, and a two-stage trigger. Add optics to fit your purpose and you’re good to go.
How about a more tactical rifle? For my law enforcement patrol rifle, I have a free-floating quad-rail handguard to assist with installation of lights, lasers, grips, or whatever. I have a new style Rock River Arms stock (similar to the Magpul CTR stock) which gives a better cheek weld, a two-stage trigger which aids in accuracy, an Aimpoint T-1 micro sight for fast sight picture, and VTac sling. It is ready for anything.
Upgrading a hunting rifle depends on what it is intended for. My varmint rifle has a Wilson stainless bull barrel and a round free-floating handguard with a bipod. I have a 4.5-14 scope so I can see ground squirrels at long distances. I have a Magpul PRS adjustable stock, so I can adjust the length of pull for prone or bench shooting. The trigger is a match two-stage for accuracy. It is a very practical set-up for varmint hunting but too heavy for carrying around all day.
For a walking around hunting rifle, I prefer a mid-weight barrel, preferably stainless. The handguard of choice for me is the Yankee Hill Machine Jarrett series – round and vented, with short rails for a light or bipod. I like the Magpul MOE rifle stock because I don’t have to worry about adjustments and it is very comfortable, both are practical considerations. My .300 ACC Blackout has a stainless Wilson Combat barrel, a Geissele SSA-E two-stage trigger, and a 1-4x scope – it was assembled as a pig hunting rifle but is capable of taking other small game at reasonable distances.
There are many other add-on components for the AR-15 platform such as lights, muzzle brakes, compensators, buffers, stocks, grips, etc. There are tools available to assist you in installing all the different add-ons to your rifle. In the video, I show dozens of examples of add-on components from various manufacturers and give you some of my reasons for choosing them. I show why some are practical, why some are great for tactical situations (whatever that means to you) and why some are just so cool you may have to put one on your rifle, just ‘cause. I also show you the tools for a barrel change and the proper method to change barrels and handguards. Check out the AGI video AR-15: Practical, Tactical, or Tacti-Cool to see all of the components and then to decide what is right for you.
American Gunsmithing Institute