So You Wanna Build An AR?

Hi, I’m Cory Sementuh and I’m the proud owner and armorer for CDS ARMS / FREEDOM SECURITY. You’re probably reading this because you’re interested in building an AR-15 style rifle/pistol/SBR and want some advice. While this is not a definitive guide, it is a great starting place for the information needed to make good decisions on your AR build. I have learned a ton in my 20+ years in the AR industry and on the innumerable amount of builds, upgrades, modifications and repairs done. I do work for everyone from first time buying Average Joes to Federal, State and local law enforcement officers and agencies. AR style rifles are a passion of mine and I’d like to share some of the things I’ve learned in my journey thus far. The AR industry is constantly changing, trends come and go, but I will provide what good advice I can as of 2022; just don’t beat me up if trends and prices change in the future! Throughout the article I’ll give you my top picks to consider, in no particular order. Please read and then ask questions!

Why Build? – Factory vs Custom Build

I run a business, and a business has to make money to survive. Time is money. It’s quick and easy to sell someone a factory AR, but I don’t like that. You don’t need any knowledge to sell a gun; you just have to collect the money and do the paperwork. That’s fine, but my goal is to educate a customer to their options to help them make a more well informed decision on their AR.

Here’s my recommendation: If you like a good quality name brand factory rifle, that has all of the specs and features you like, and you don’t intend to make (m)any changes to it, then buy it! You’ll have a nice rifle ready to shoot quickly that offers a full factory warranty. There are a few reasons to go factory. Maybe you love a brand, want a certain proprietary feature nobody else offers, desire a specialty piston gun (always factory on pistons!) or perhaps your work dictates you’re only allowed to use rifles of a certain brand or type. I’d be happy to critique your prospective choice in a factory gun and quote you a price! Of course you can always take a factory rifle and make changes down the road, but you’ll likely pay more. Factory rifles can be great in the right circumstances, but I’m certainly biased toward building! Remember, you can never upgrade a sub-par factory rifle into a quality rifle without almost building a whole second new gun. Usually it doesn’t make financial sense! My advice for a factory rifle is to buy higher end or boutique and be happy. For a mid-tier factory rifle, you can almost always do better with a build in performance and most importantly price!

Cory’s Picks: Colt, Daniel Defense (DD), Knight’s Armament Corp (KAC), Geissele, Lewis Machine & Tool (LMT), Bravo Company Machine (BCM), Noveske, Radian, Primary Weapons Systems (PWS)

I’ll be honest and say I don’t own a single factory AR. If you plan on having certain parts or features that the factory rifle lacks or just want to save money and have a nice end product.. Custom ARs are the best! You get to spec out every part and piece, use quality components and ensure you get exactly what you want and nothing you don’t! You can elect to spend more money on the more important pieces and save money on things less significant. All at a significant cost savings over taking a factory rifle and removing perfectly good parts, tossing them aside (they usually have little resale value) and replacing them with other new parts. It’s usually a poor economic choice. Not to mention upgrading some rifles just can’t be done with some of the proprietary parts or just aren’t considered a best practice due to the style of the factory setup. Quick example: Take a basic factory fixed A2 front sight base style upper and reconfigure it to a modern sleek free-floated handguard style upper. It usually doesn’t make sense cost wise versus just adding a new barrel, upper receiver and gas system to have a whole second upper receiver.

Note 1: Saving Money: Right off the bat you’ll save 11% on building vs buying a factory rifle. The Feds place an 11% Firearms and Ammunition Excise Tax (FAET) on any new firearm and the manufacturers have to pass this cost along in their pricing. Piece together an AR and you aren’t subject to the tax! Not to mention the money you’ll save on getting the exact parts you want, so read on.

Note 2: Basic Budget ARs: You get what you pay for, an adage as old as time. To most people, a basic factory rifle may check all the boxes and provide them fantastic performance when they shoot one mag twice a year out of it.. To others it just won’t cut it. If you’re reading this you may be looking for more! A giant gun manufacturer may make an awesome pistol or hunting rifle or shotgun, but they just normally aren’t equipped to make a quality AR. I don’t want to sling dirt and name names here. Many big gun companies are only making an AR to be trendy; everyone else is doing it! They have the household name advantage. They aren’t going to make parts in house or be innovative. If you must save a few dollars and get a less inexpensive factory rifle, Smith & Wesson is as cheap as I’d personally go. A cheap AR is what I like to call a “price point gun”. It’s made to survive in a sea of other cheap ARs and be stocked on a dealer’s shelves at a competitive price. The big gun corporation doesn’t care about you and your gun, they care about making an extra $7 per rifle to increase their bottom line and appease their shareholders. The sad reality is that the largest manufacturers are the ones who could afford to put a little more money into their builds to make or source higher quality parts. They could put an extra $20 into each rifle and make something nicer, charge $40 more and profit, but it makes more sense to save the $20 and multiply it by 10’s of thousands of guns and profit! When it comes to quality you just normally can’t get it in a large assembly line approach.

Note 3: AR Build Kits: Let me just toss out my opinion. Most of the cheap AR build kits on the market are just that; cheap. Some of these vendors are the Wal-Mart of guns, pumping out the cheapest parts from some unknown source (sometimes foreign, yikes!) to bring you a kit that appeals to your pocketbook more than your sense of quality. Sometimes the parts are blemished, seconds or lower bin tier parts offered at a steep discount. They often have house brand type handguards or furniture (stocks, grips, accessories, etc) made for them that look kinda fancy, but are often basic, sub-par designs. Your mileage may vary. Guns are often long term purchases. I don’t want to rely on the support of mega big retailers to ensure that my parts fit together, work, or last as intended. I’d honestly rather avoid this gamble unless you go into it knowing it’s a range toy. Now don’t get me wrong, there are other qualified vendors on the market offering kits with high quality house and brand name components. Kudos to them!

Note 4: Specialty AR Manufacturers: Many AR “manufacturers” don’t “cut chips” and a good majority don’t machine a single part in house. Like myself they may be a boutique builder selecting known good parts from OEM style vendors or having parts designed to their specs and machined by a 3rd party. There’s a bunch of larger AR brands who follow this model, you’d be surprised! This is generally good, as the assembler can perform QC on the parts and control the build process, but again you can likely build something similar using known good parts and save hundreds in the process! If your favorite brand buys an upper receiver from Vendor X and then laser engraves their logo on it and marks the price up $20, did they add $20 of value into the part, and will you gladly pay more for it? Ask me if you have any specific questions here.

Note 5: Quality and Quality Assurance. This is a big one for me. A lot of people need to hear this. *Almost every company in the industry can make a functional and reasonable quality gun.* Yes, lower price point guns can be done properly. Yes, top tier rifles can and will have problems. The main point is how often do these brands really have issues? The fact that most people overlook in their quest to either bash brands or elevate and justify the things they own is this: consistency is key. How consistently can a given company do things properly? How often do they catch the issues they do have and fix them before they ship to customers? How often do their warranty replacements have issues? What sample sizes are people measuring across to find their data and make their assumptions? Take that for what you will. I can almost guarantee you know one person who has brand X and just because they never had an issue with that one thing, they now think it’s the best. Is it? Some only want to argue brands and not the why behind them. By taking person accountability and attention to detail on every build I do, I can confidently say I bring more to the build than a factory assembly line of workers.

CDS ARMS AR-15 Builds

My philosophy when it comes to AR builds is simple. I want every rifle to be something that I would be proud to own. To contain quality parts, be personalized to the owner’s usage and style, and provide many years of reliable service. I have a solid recipe I’ve been following for years and hundreds and hundreds of rifles. I know what parts interface well and result in a quality AR at a reasonable price point. From there we can go as basic or Gucci as your desires and budget allow! There are many, many unique styles and types of AR rifles, please don’t hesitate to ask me about your dream build! I have an interest in most all types of ARs from military clones to competition rifles to lightweight builds to benchrest accuracy to hunting rifles and every setup in between. This article will focus on the concept of a “Duty Rifle”.

Here are the things you can pay me to do:

  1. Design and spec out your AR build to ensure compatibility and reliability of parts. This is seldom used, for those who need info and advice and want to do the rest themselves to purchase and build. (Design fees are refundable off build or parts purchase)
  2. Sell you a box of parts to assemble yourself
  3. Give you partially assembled parts, perfect for those who already have a lower or want to try to build part of the gun themselves. The upper is usually trickier for those who lack the tools and skills to assemble.
  4. Provide a full turnkey rifle ready to shoot. Most people pick this option.

$1000 is a reasonable starting budget for a build. We can go a little lower or many hundreds or thousands higher. AR builds can go mild to wild!

I’m a simple guy and I try to make this easy. Together we make choices on parts and come to a conclusion on your perfect custom AR. I spec out the build and provide you a price on the full build as a flat-top rifle (no sights, accessories or optic). Then we add on anything else you want to reach a total price, less than you could source the parts for yourself retail. The more stuff you buy at once the more I can save you! I don’t charge any kind of “assembly”, “build” or “shop” fees on top of the parts for a full build. The only thing I’d have to charge you for would be additional gunsmithing or armorer work on some existing rifle upgrades, modifications or repairs. I do the builds one at a time, following the correct assembly procedures, using the correct tools, the correct materials and the proper specs and attention to detail.

Note 1: Build Process: I use the methods and techniques taught in Colt and other OEM’s LE/Mil armorer’s courses as well as my experience over the years to assemble. What sets an armorer like myself apart is the attention to detail and the quality of the finished product. If you build it yourself.. Are you using the correct tools, the correct assembly procedures, the best practices, the correct lubricants, the correct torque specs, fitting parts as needed, etc? Or are you just hammering punches and screwing together parts until “done”? If you mess up or have an issue can you fix it? If you lose or break a small part, can you replace it? Not to make this sound like you need to be a brain surgeon rocket scientist, but there are several things you can do during assembly to make a more reliable and better finished product. It’s sometimes the small things that matter, which often get lost in the modern large scale manufacturing process. I won’t share all my secrets, but to throw out a few things: I’ll properly torque and seat your barrel nut to the correct spec to provide the best accuracy. I’ll install parts in such a way to make them semi-permanent and stand up to years of hard use. I’ll dimple your barrel for a gas block to ensure that it provides a life-long service free of issues and won’t shoot loose. I’ll properly torque (and optionally stake if desired) your receiver end plate (castle) nut to ensure a rock solid hold. I’ll perform a Limited Technical Inspection on the rifle and Quality Assurance checks to ensure it meets my stringent standards. All of that and more is included standard on all builds. If you have certain needs in mind we can also discuss additional specialty services for your new build or existing setup.

Note 2: Warranty: A custom build implies that you have a warranty on each individual part from the manufacturer of said part, as installed by a qualified gunsmith. I will personally warranty my builds for labor defects in workmanship for as long as I’m in business and I walk this earth with full use of my hands, eyes and mind. I’m a nice guy and I’ll cover everything but stupid. It’s a rarity but sometimes the worst happens. If something breaks I’ll help you contact the vendor of the part and seek a replacement, then assist with getting the rifle back up and running. If you stick a 300 BLK round in your 556 chamber and kaboom your upper, or smash the upper in your vice while attempting a home mod, or get 15+ squib rounds stuck in your barrel then I’d be happy to quote you parts and labor for the repair. These scenarios and more have all happened, yikes! This limited warranty I offer is extremely standard, don’t let it scare you. I’ll help you out so long as I can!

What’s a Duty Rifle?

To me, a “duty rifle” is an all around good, general purpose carbine, light and handy, with quality parts, that will perform to a high standard. Something that can be used and even abused, and be something you can trust your life to. My motto with AR builds is to never cut corners and recommend subpar parts. The cost savings just isn’t worth it. I can’t quantify saving a small sum of money now to give up so much in the future. I don’t want to cut corners now to penalize myself later. I want the rifle to meet (and ideally exceed based on budget) a certain baseline standard. I want the same rifle for the guy who shoots at paper twice a year to be the same as the police officer using his rifle to train and defend on duty or the competitive shooter who shoots a case of ammo every week. To me a duty rifle is the “best for the money” approach without the negatives associated with buying an overpriced name or paying too much to upgrade a lesser rifle. I take pride in making every rifle I build a quality piece that I’d be proud to own and shoot myself. I tend to learn toward the style of rifle and the parts that are used hard and tested by police and military type users in the real world, without all of the extra fluff.

Parts Breakdown

Some customers come to me having never ever held an AR-15 before, and some have 30+ years of experience and a full parts list ready to go. If you’re just starting out I recommend you take a basic approach. Google for “AR-15” and take a look at the thousands of pictures to see what kind of style you like. Chances are we can take a similar cosmetic route using quality parts for a finished product you love! Some people just need to touch, feel and try different options to see what works best for them. I’ll show you what is popular and go from there. We can approach each build in a customized way! One thing to understand with a build: Any time you take out a basic part and put in an upgraded part you’re paying only the cost difference on the part. It always makes sense to use a fancier part you want from the start rather than pick a basic part and then later upgrade to something else at full cost. I’ll break this down better during the build consultation process. When doing a build workup it’s better to include every feature you want and have me quote that. It’s far easier and nicer to remove parts/features from a build if needed to bring the cost down than to simply answer “How cheap of a build can you do?”. Remember your goals for the rifle in sight and work from there.

Note 1: Mil-Spec: There’s a concept called Mil-Spec. It used to mean something. In my opinion, in the year 2021 with the modern AR industry, it’s mostly meaningless. The term gets tossed around to mean that a part meets a certain type of spec used on military rifles and/or that it fits a “normal” AR-15 style firearm. It’s the same type of term that “tactical” is. Realistically there are many parts on the market that wouldn’t meet “mil-spec” but would actually far exceed it in performance, longevity, etc but it isn’t on a mil M4 so it’s not really “mil-spec”. I’ll still call parts mil-spec but normally this means that it is correct in style, design, function or will exceed a certain a spec. Don’t sweat it and focus on the important details of the part instead. I won’t bore with large amounts of technical details in this article on materials choice, heat treating, coatings/finishes, testing, QC, etc, but we can discuss this further as needed. Gone are the days of a carbine length gas system and a set of plastic handguards affixed to an A2 front sight base. It just isn’t modern!

Note 2: OEM Parts: OEM stands for “Original Equipment Manufacturer”. This means they are components make by a 3rd party (OEM) manufacturer and used in assemblies of other manufacturer’s products. This is extremely prevalent in the automotive and electronics industry. Guess what, the gun industry is just as bad! Just because a part doesn’t have a “brand” attached to it doesn’t make it bad. Many AR parts are not able to be traced back to who actually physically made them. If the part is from a trusted source and meets the proper standards it can be a fantastic part and value. Remember this, as it’s the way to save some money on a build. Spend the money on the important parts and save the rest for others. Just beware of shady parts sources and deals that are too good to be true. Unless you’re buying in the 1000’s of minimum order quantities you aren’t going to see magic part prices well below the market trend.

Note 3: Enhanced Parts: I call fancy upgraded AR parts the “Bells & Whistles” on a build. These are generally parts that are enhanced from the basic mil-spec style component. Some are 100% cosmetic and others are a genuine enhancement to the AR platform. It’s up to you to make the decision if the “upgrade” is worth it. There’s many trains of thought here, and I’m always happy to share my opinion. I do like ambidextrous controls, and sometimes a little extra splash of color and design won’t hurt! Like everything, some parts are better than others and I’ll go into this more below. If you haven’t figured it out yet, there’s some company who thought they could get rich by making some fancy part and brought it to market! I like to keep my builds simple and effective but modern by taking advantage of upgraded and enhanced components.

Note 4: Color & Design: As you take a look at components be aware that most furniture (stocks, grips, rail panels, sights, etc) are available in several different colors or designs to make a unique build. AR rifles are highly customizable so you aren’t forced to stick with basic black if you don’t want to! Besides black the most popular colors are Flat Dark Earth (desert tan), Gray, and Olive Drag (OD) Green. If the colored furniture isn’t enough I do offer services for custom Cerakote paint as well as laser engraving for logos, text and designs. Personally I like to keep things simple and run black main parts with a splash of color from the contrasting furniture, but we can go wild with color and style if desired!

Let’s dig deeper into the details: I like to take a bottom up approach with the build parts. We’ll start at the lower receiver, then move to lower components and furniture, then to the upper receiver, barrel, gas system, handguard and finally to sights/optics and accessories.

Lower Receiver

The lower is the “firearm” as per Federal and State law that has the serial number and must normally be transferred with a dealer involved. Every other AR part is freely bought and sold as a part. You must be 21+ years of age to buy a lower and a resident of the state of Pennsylvania (or I can ship to a local FFL dealer in your home state). I’ll sell you the lower receiver with the normal paperwork and PICS background check then provide gunsmithing services off the receiver to assemble your full rifle. Or if you have an existing lower or rifle we can build from that. For lowers there’s two main types; Forged and Billet. Most lowers are forged and that is a mil-spec lower. Forged lowers start life as a forged shaped block of aluminum that has been finished machined and coated by a shop. Billet means that it’s a receiver milled from a solid block of aluminum to finish. Billet lowers are ever so slightly weaker than forged so to make up for it they are often beefier, blockier or thicker in certain areas, which many consider to be a nicer cosmetic effect. The billets can be fancier and can definitely be much more expensive, it’s all in what you want. For a normal build, stick with forged and be happy. Let me share some info. There’s only a small handful of forging houses making forged lower slugs today. Then there’s a ton of places doing the finish machining and annodizing or paint. That being said, there’s a very small number of shops doing variance marked lowers for a large number of smaller manufacturers. As in one place is making lowers for 100 different brands. So long as the lower is in spec, there’s really no huge difference between various lowers, with a few exceptions. The rollmark AKA picture on the side of the lower is a primary concern for most, so pick your favorite brand name and picture and be happy! Note, some lowers do have fancier features which may stem from custom forgings or billet designs, such as flared magwells, reinforced areas, etc. Those are not mil-spec features, but something you can consider. Also you’ll find that some manufacturer’s lowers are not available stripped, only available as a completed lower assembly or not available as a lower at all. For example you can’t easily buy a Colt lower, only a full rifle. For a simple and solid build pick a standard forged lower.

Cory’s Picks: Aero Precision, Spike’s Tactical, Ballistic Advantage, Stag, Geissele, Noveske, BCM (Full lowers), Your Favorite Brand

Lower Receiver Parts Kit

The lower receiver parts kit (LPK) contains the fire control group (trigger, hammer, disconnector, safety selector) as well as the other major components (mag catch, bolt catch, buffer detent, etc) and all of the little pins and springs to assemble the majority of the lower receiver. Here’s my advice. If you don’t know the difference by experience of the differing parts I’d suggest just using a mil-spec style parts kit. The LPKs I use are sourced from good quality vendors and should provide a nice base for your build. If you want to upgrade stuff, the sky is the limit! High end triggers and fancy bolt catches and selectors, etc. Here’s a few tips: A trigger upgrade can be great, there’s options from around $50 to $300+. There are nice options for upgraded or ambi bolt catches, mag catches and selectors. An enhanced trigger guard for aesthetics and shooting with gloves is another fantastic upgrade. Lots of great options if you will use the features! We can discuss this more in depth.

Cory’s Picks: Quality OEM LPK vendor, Geissele, ALG Defense, Radian, Seekins Precision, Battle Arms Development (BAD)

Buffer Assembly

The buffer assembly (Buffer Tube, Receiver End Plate, Castle Nut, Buffer & Spring) are essential to the functionality of the AR style rifle. Always picks a “Mil-Spec” over a “Commercial” style tube. There’s a size and small strength difference there. The standard mil-spec parts work for the hardware, but I do tend to recommend using a quick disconnect (QD) style receiver end plate here for additional sling mounting options. It’s not very expensive and quite handy. For the buffer and spring there are some options. Skip the basic el-cheapo carbine buffer and run the (H) Heavy buffer to help the rifle run well and provide good functionality. There are several different types of buffer weights and some specialty buffer springs, but I’ve found that a H buffer style weight and a quality carbine spring will run most rifles well. Of course there’s always variables here to discuss as needed.

Cory’s Picks: Quality OEM Mil-Spec Buffer Tube, BCM QD End Plate, Heavy Buffer, Carbine Spring

Pistol Grip

The “free” pistol grip option is the black A2 pistol grip. It’s great for a basic M4 or military clone but certainly not modern or popular. The skinny design and finger grooves don’t tend to fit many hands well. With most pistol grips $25 or less it’s a nice upgrade to go with your favorite design and color to customize your rifle. Pick something that fits your hand well, has the correct grip angle and suits your style. I personally pick the textured or rubberized grips with a more steep angle to coincide with modern shooting style and shorter rifles.

Cory’s Picks: Magpul MOE K2, Ergo SureGrip, BCM GunFighter


The buttstock of the rifle really impacts the look and feel of the AR. Differing sizes, shapes, designs and colors makes this an essential part of the rifle. The basic M4 stock isn’t really all that cheap, so it makes sense to spend a little more to get what you want here. A quality stock will be light, strong, provide good cheekweld, be tight, adjust well and overall be functional. A cheap stock will be loose and rattle and not provide a repeatable platform to sight and shoot your AR. Some stocks are fancier and have different sling attachment points, tube locking features, etc that make them unique. Pick what fits you well and looks best in your mind.

Cory’s Picks: Magpul CTR/STR/MOE SL-K, B5 Bravo/SOPMOD, Bravo Company Gunfighter/SOPMOD, Mission First Tactical Minimalist

Upper Receiver

Moving onto the top side of the AR. The upper receiver is the major component that contains the bolt carrier group and charging handle and has the extremely important job of affixing the barrel to the gun by means of a barrel nut and a handguard assembly. Quite an important piece as a whole. The upper receiver itself is identical to the lower in that it can be Forged or Billet. You’ll likely want to match the upper to the lower style so everything looks and fits together nicely. A normal duty rifle is going to have an OEM style forged A3 flat-top upper receiver. There really isn’t a big difference on uppers so long as you pick a quality offering from a reputable source. Or you pay more because some company engraved their brand name onto it. Some upper have “T marked” slots on the picatinny rail sections on the top, others do not. To me this is irrelevant unless you have a need to install and remove sights/optics/accessories often and will use the reference marks. Most people set it and forget it. The upper will have an ejection port door which can be customized if desired with graphics and text as well as a forward assist, unless something specialty is picked.

Cory’s Picks: OEM A3 Forged Flat-Top Mil-Spec Upper, Matching Billet Upper


Barrel selection on ARs can be controversial and have many differing opinions. Barrels are something that can cost sub $80 or more than $800 depending on what you choose. For a normal build this is an area where I ask people to trust me unless they have a specific need or desire in a barrel. I can recommend a quality barrel that will shoot well and have a good service life. Of course we can also consider more premium style barrels in 223 Wylde, different twist rates, profiles, stainless steel, fluted, etc. Many, many variables when it comes to barrels. For a duty rifle I want something that is going to be a reliable, hard use barrel, offering sufficient accuracy and take a large round count. I like a real 556 chamber to handle all ammunition types. A chromoly steel construction with nitrided surface treatment for durability. A government, medium or M4 style profile for a reasonable weight. The mid-length length gas system for a soft shooting rifle with sufficient dwell time and less gassy operation. A 1×7 or 1×8 twist for a wide range of bullet weights. A standard 1/2″-28 thread pattern for standard muzzle devices. Let’s not over complicate this article and handle specific barrel discussions as needed.

Cory’s Picks: OEM Style: 16″ Government Profile, Chromoly, Nitrided Finish, 556 NATO Chamber, Mid-length Gas System, 1×7 Twist, 1/2″-28 Threaded – Brands: Ballistic Advantage, Rosco, Daniel Defense, BCM, Faxon Firearms


The handguard or “rail” is another extremely important part of the AR rifle and a major component of the overall style and feel. While we can go with anything from old school plastic handguards, chunky picatinny quad rails, to unpopular or proprietary attachments, I’ll jump right to the chase and make a good recommendation for today’s carbine. Your duty rifle is going to want a modern, lightweight, sleek and long MLOK style handguard to provide a stable upper and free-float your barrel. MLOK is the current standard picked by the US Military and many police forces due to way it excelled in testing and usage. MLOK provides a super slim, low profile, surface mount design with no sharp edges to mount accessories with good strength and repeatability. I’d recommend a handguard in the 12″-15″ length for a 16″ barrel to ensure a long tucked look. There are some cosmetic and functional differences to consider between brands and models, but you will have the best setup if you choose a quality offering. I’d 100% recommend not trying to skimp with the AR handguard. Most good handguards are $150-200+. Anything much less is likely to be foreign made and lack quality or have shortcomings. I have seen too many rails over the years that had serious flaws in their design causing the handguard or barrel to become loose during normal use, cause poor accuracy due to misalignment of sights or barrel, rotate, twist, or even pull off of the barrel nut. The handguard is the largest piece of the rifle and one of the main parts you interface with as the shooter, so choose wisely. I’d be happy to discuss my favorite handguards with you and critique any potential choices.

Cory’s Picks: Geissele, Bravo Company, Midwest Industries, Troy Industries, SLR Rifleworks, Seekins Precision, 2A Armament, Aero Precision

Gas System

The AR gas system will refer to the gas block (GB) and gas tube. For most builds I use an OEM style nitrided low profile gas block that is entirely under the handguard. Normal gas tubes are made of stainless steel and are silver colored. For a few dollars more you can have a nitrided or black oxide coated gas tube which looks nicer and potentially withstands the heat a little better. You won’t find many problems with a reasonable low profile gas block, but there are fancier models on the market if you so desire. Some higher end gas blocks offer a tighter fit which can reduce gas leakage and carbon buildup. There are also adjustable GBs that can be used for specialty needs, different calibers, etc to help tune a rifle. For most purposes take my advice on a simple GB unless needs dictate otherwise. I will properly dimple your barrel and set the screws/pin to make the gas block a semi-permanent installation.

Cory’s Picks: OEM Low Profile Nitrided Gas Block, Geissele Super GB, Superlative Arms Adjustable GB, SLR Rifleworks Adjustable GB

Muzzle Device

I’ll give you my simplest advice. Use a standard cheap A2 flash hider unless you’re going to run a silencer with its specialty mount or you have a goal in mind that would necessitate a different flash hider and compensator. Otherwise you’re just blowing money to make your gun look fancy or overly loud. With normal 556/223 duty rifles there just isn’t much sense to change this, but other calibers or builds may dictate otherwise.

Cory’s Picks: A2 Mil-Spec Flash Hider, Silencer Mount

Bolt Carrier Group

The AR-15 Bolt Carrier Group (BCG) is a critical part. It touches every round fired and is essentially the workhorse of the entire rifle. It is responsible for loading, chambering, firing, extracting and ejecting every single round. It gets hot and dirty and grimy and takes a lot of wear and tear doing it. The BCG is another place to not try and save money on an AR. Luckily, good quality BCGs are not much more expensive (if any) than lesser quality units.
There are many different style carriers on the market, however modern day you will see two main varieties. The AR-15 semi cut carrier and the M16 full auto style carrier. I am a huge fan of the M16 auto carrier as it adds a little extra mass to the BCG helping to retard the guns cycling and create a smoother action. Before you ask, yes the full auto bot carrier is legal in normal semi auto guns. There’s literally no reason to pick a semi carrier these days. We could have a long discussion on BCG materials, heat treatment, testing, coatings, etc, but let’s spare that here. My advice is to buy a quality brand BCG or an OEM unit with good specs and shoot your rifle. If it eventually wears out then you replace it and move on. My go to for most builds is a modern M16 BCG with a Nickel Boron (NiB) or Titanium Nitride (TiN) coating. Many argue this, but I’ve always found the coated BCGs to clean up easier and require less lubrication than a mil-spec parkerized BCG. If you don’t like the NiB silver or TiN gold color there are fancy black coatings on the market or even a hard nitrided finish. Take my advice on this part or we’ll chat about your best option here.

Cory’s Picks: FailZero Nickel Boron, WMD, Daniel Defense, BCM, Sionics, ToolCraft, Quality OEM M16 BCG

Charging Handle

The charging handle (CH) is another piece you’ll interface with quite often on your rifle. The CH is used to charge or load the rifle for the initial shot. It’s also used by some shooting techniques at every mag change, as well as being essential in malfunction clearing and unloading the firearm. The standard mil-spec charging handle has a tiny latch on the left side that is pinned to a small wing of aluminum on the rear. It’s a functional piece but severely lacking in my opinion. Many companies have created an enhanced CH latch or an entirely redesigned CH that works wonders for quick and effective modern weapons manipulation techniques. My recommendation is to take the upgrade path and utilize a quality ambidextrous double sided enhanced latch design. You’ll enjoy it every time you shoot! I’ve made it a standard feature on most builds to feature a Radian Raptor LT charging handle due to the great design and reasonable price.

Cory’s Picks: Radian Raptor, Geissele Super Charging Handle, BCM Gunfighter


A semi automatic firearm is only as good as its ammunition feeding device. The AR relies on a good quality and reliable mag to function 100%. In my opinion Magpul is the best. I personally want the newest Gen M3 PMAGs. Colored or Windowed is irrelevant. If you want metal mags, the mil-spec aluminum or steel mags should also treat you well. Remember a mag is a cheap, disposable item. Run them until they don’t work well and then delegate them to range duty only and eventually toss them out.

Cory’s Picks: Magpul PMAG 30/40 Gen M3, Lancer, Mil-Spec Style Metal

Sights / Optic

I’m a huge fan of the small red dot, holographic or prism type optic for the AR platform with complementing flip down back up iron sighs (BUIS). Others are more keen to a scope type optic, or even simple iron sights, but that really depends on your anticipated usage. Here’s my advice. If your budget allows, step into a market leading optic from Aimpoint, Trijicon, Eotech, etc and run a nice set of low profile metal BUIS on the rifle to finish it off nicely. If you want to keep it simple and significantly cheaper look into one of the less expensive but still good options out there from Holosun, Sig, Vortex, Primary Arms, etc. Some may even elect to skip the BUIS to save some cost, but do consider the cheapest option in the Magpul MBUS line offering nice polymer sights. Sights and optics are a very personal choice but quite essential being the method for aiming the gun.

Cory’s Picks: Sights: Magpul MBUS/MBUS Pro, Troy Battlesights, Knight’s Armament Micro – Optics: Aimpoint, Trijicon, Eotech


In my opinion a rifle needs some bells and whistles to be it’s best. I’ve covered the bases with the parts above and if you want a more fancy and modern carbine I do recommend ambidextrous controls. Charging handle I find most important, and the ambi selector is nice. Also I like some type of support hand handguard accessory such as a vertical grip, angled foregrip, handstop or even rail panels. A duty rifle can really could benefit from certain add-on features as well. Optic, sling and white light being key. A silencer is certainly recommended. Anything you need to use your new AR effectively I can assist with. Cleaning supplies, mags, ammo, case, accessories, etc, I’d be happy to help with. Let’s discuss your needs and I’ll see how I can package everything together for you to save the most!

Cory’s Favorite Recipe

Here’s a freebie on a recipe for a nice duty rifle. I’ve built this style rifle hundreds of times and am quite happy with it. To me it has the best combination of features, functionality and modern, popular design:

Stripped Lower Receiver (Aero Precision, Spike’s Tactical, BCM, etc)
Mil-Spec Lower Parts Kit
Enhanced Trigger (Geissele, ALG, CMC, Timney, AIM SSTAT, etc. Optional but useful feature, can drop it and save a few bucks)
Ambi Selector (Optional but useful feature, can drop it and save a few bucks)
Enhanced Trigger Guard (Optional but useful feature, can drop it and save a few bucks)
Pistol Grip (Magpul, BCM, B5, Ergo, etc)
Buttstock (Magpul, BCM, B5, LMT, Mission First Tactical)
Mil-Spec Buffer Tube
Heavy Buffer & Spring (H, H2, etc buffer selection is essential for proper functionality)
B5 QD End Plate & Castle Nut (Optional but useful feature, can drop it and save a few bucks)
Mil-Spec A3 Upper Receiver
Upper Receiver Parts Kit
16″ 556 Nitrided Midlength Gas, 1×7 Twist Barrel (Ballistic Advantage, Roscoe, BCM, DD, etc)
Low Profile Nitrided Gas Block
Mid Length Nitrided Gas Tube w/ Pin
A2 Flash Hider & CW (Or silencer mount)
13″-15″ MLOK Style Handguard (Midwest Ind, BCM, Geissele, 2A Armament, Seekins, etc)
Ambi Charging Handle (Radian, BCM, Breek, etc. Optional but useful feature, can drop it and save a few bucks)
M16 Bolt Carrier Group (I like Nickel Boron and coatings. Quality choices only, this is the heart of your rifle)
Red Dot Optic (Aimpoint, EoTech, Trijicon, Sig, Vortex, Primary Arms)
Backup Iron Sights (Magpul, Troy, Griffin, KAC, etc. If you want to save money run a red dot for now)
Magpul PMAGs

I’m not big on gimmicks. This rifle has everything you need and nothing you don’t. No extra do-dads hanging off the side, just useful, tried and tested component selections. The parts that are enhanced are tasteful and useful and will enhance your competency when training on the AR platform and not hinder it. There are ambidextrous parts, extra sling mounting options and a solid selection of parts. I like it!


If you’ve read this far, thank you! I hope you have learned something about AR-15 builds and my philosophy on a modern fighting carbine. My best advice is to start with a nice rifle setup and receive quality training from a competent instructor. Good luck and shoot straight! – Cory