Here are 11 best AR 15 rifles right out of the box you can buy right now including standard and higher end models.

Our selection criteria were based on thorough assessments of their performance track records, modularity, aesthetics, and cost, ensuring that you get the most reliable and valuable options right out of the box.

While the core functionality of most AR15 rifles remains consistent, the typical price difference is often based on the added accessories included.

Disclaimer: Some links contain affiliate offers which only generate commissions when the visitors make purchases. 

Most Accurate AR-15

These are the major items to pay attention to when shopping for an standard 16" barrel length AR15 rifle.

ar15 legacy to modern

The AR 15 platform has undergone significant evolution, allowing for endless customization possibilities. It's worth noting that factory rifles can always be customized later, providing you with even more upgrade opportunities later.

For beginners, most AR 15 rifles available today are well-built and reliable. While the price range may vary, the key differences between a standard $800 AR15 and a more advanced DDM4v11 costing $1800 are the brand, markup cost, and additional accessories.

If you're looking for a rifle that comes equipped with the accessories you want right out of the box, we highly recommend purchasing one rather than opting for a bare-bones $600 AR15 that requires additional parts and could end up costing more in the long run.

However, if you prefer to create a customized rifle that meets your exact preferences, then feel free to do so. The possibilities are endless, and the end result will be a rifle that is uniquely tailored to your needs.

See more in the FAQ section

Best AR15 Picks [5.56mm All Categories]

Daniel Defense M4V11 - Best Overall

daniel defense DDm4v11
  • 7075 T6 Aluminum Upper & Lower
  • 18" Barrel + Muzzle Device
  • 15" KEYMOD Handguard
  • Direct Impingement
  • 1/2" -28 Muzzle Thread Pitch
  • Type III Hard-Coat Anodized
  • 1:7 Barrel Twist
  • Mil-Spec Buffer Tube
  • Daniel Defense Grip & Stock

What makes the DDM4V11 Special - The Daniel Defense line of AR rifles are one of the top tier brands in the firearm industry, which also known as one of the companies selected by US DOD as the Sole Provider of the RIS II rail system for the M4A1 SOPMOD II weapons system fielded by USSOCOM.

All DD rifles are made to the US DOD Mil-Spec standards, and the DDM4V11 is a super lightweight AR with modular handguard right out of the box, which is great for new AR buyers.

Free Float Rail System With Plenty Of Mounting Space - the V11 model provides the shooter with a low profile & long 15" long SLiM handguard rail system for supporting hand extended out closer to the muzzle allowing them to drive the gun more precisely and prevent over travel when transitioning between multiple targets.

Smoother Recoil Impulse - Smooth recoil lets the shooter for quick and precise rapid-fire, the 9" mid-length gas system allows that type of performance compared to a 7" gas system

Ambi Safety Selector - Lefties and righties can operate the safety selector without buying an aftermarket selector, and it's Ambi ready right out of the box

Non-Wobbly, Tight Tolerance - Unlike cheap AR15s, the whole rifle from the front to the end feels sturdy without any wobble, which is the first sign that demonstrates the good qualities of the rifle

What are you really paying for - You are paying for the tight tolerance built receivers, mil-spec qualities, the unique 15" long rail, and the Daniel Defense brand.

Ruger 556 MPR - Best Multi Purpose

  • 7075 T6 Aluminum Upper & Lower
  • 18" Barrel + Muzzle Device
  • MLOK Handguard
  • Direct Impingement
  • 1/2" -28 Muzzle Thread Pitch
  • Type III Hard-Coat Anodized
  • 1:8 RH Barrel Twist
  • Mil-Spec Buffer Tube
  • Magpul MOE Grip & SL Stock
Ruger AR556 MPR

What makes it multi-purpose - The Ruger MPR has all the modern AR15 accessories right out of the box at an affordable price, and it serves a great foundation for you future custom build.

Right out of the box it comes with high quality aftermarket Magpul stock, and grip, Radial port muzzle brake, Elite 452 AR trigger and M-LOK rail system.

Ready for competition - The included Ruger radial muzzle brake significantly reduces felt recoil and muzzle movement for fast & accurate follow-up shots

Staked gas key - Improved resistance to hot gases allows the bolt carrier to last long via chrome-plated design and staked gas key without getting loose after extensive firing

Free Float M-LOK Handguard - Increased accuracy with free-float handguard for accuracy, and provides the shooter plenty of accessory mounting space using M-LOK accessories

Sig Sauer MCX - Most Modular

sig sauer mcx with eotech exps3 fde
  • 7075 T6 Aluminum Upper & Lower
  • MLOK Modular Handguard
  • Piston Driven Gas System
  • Matchlite Duo Trigger 4.1 lb Pull
  • 9", 11.5" & 18" CHF Barrel
  • 5/8" - 24 (300BLK) 1/2" -28 Muzzle Thread Pitch
  • Type III Hard-Coat Anodized
  • 1:5, 1:7 & 1:8 Barrel Twist
  • No buffer tube
  • Sig Sauer Polymer Grip

Why people love the MCX - The Sig Sauer MCX is the first ever short stroke gas piston AR alike rifle design that gained a lot of popularity in the industry even more so than PWS.

The system is inherited from the SIG 9mm MPX, and it has been a huge sucess. Now the MCX is available in various models including:

  • 5.5" barrel Rattler (300 BLK & 5.56)
  • 9" barrel VIRTUS (300 BLK & 5.56)
  • 16" barrel VIRTUS Patrol (5.56)

In addition, the MCX rifle has more than hundreds of configurations utilizing its quick detachable barrel & stock design, and the free float modular handguard system to configure the rifle exactly the way you want.

Non-interrupted Top Rail - Continuous top rail allows the shooter to have the flexibility to mount optic and accessories any where they want

Fast & Simple Barrel Removal & Exchange - The QD barrel system makes the MCX more configurable from converting among SBR, SPR & DMR as well as calibers using just a allen wrench

Sig's Proven Internal Reduced Recoil System - The piston driven design shifts the recoil impulse away from the shooter's shoulder for a soft low recoil shooting experience

Included Matchlite Duo Trigger - Unlike a stock trigger that most AR rifles ship with, the Matchlite Duo Trigger is a 2 stage trigger right out of the box to provide the shooter a short take up (4.1 lb) crisp and clean trigger pull for fast follow up shots & long range precision shooting

Same AR15 Controls - Don't let the name MCX confuse you with a different rifle, the overall operation of the rifle is exactly like an AR15. Anyone who is familiar with the AR15 can pick the MCX up and know how to operate it

Daniel Defense MK18 - Best Short Barrel AR

  • 7075 T6 Aluminum Upper & Lower
  • Daniel Defense RIS II Picatinny Rail
  • Direct Impingement
  • Mil-Spec Standard trigger
  • 10.3" CHF Barrel
  • Mil-Spec buffer tube
  • 1/2" -28 Muzzle Thread Pitch
  • Type III Hard-Coat Anodized
  • 1:7 Barrel Twist
  • Daniel Defense Stock & Grip

What makes the MK18 the gold standard for AR15 SBR - When the USSOCOM needed a combat proven shortened version of the M4 for easier to use in and around vehicles and in tight confined spaces, the MK18 is the final iteration of the M4 CQBR development.

Get What Spec Ops Members Use - The 10.3” barrel MK18 is the same length in use for the MK18 upper most commonly used for CQB operations fielded by US Special Operation Units

Uncumbersome For CQB Actions - The MK18 is the most reliable short barrel AR rifle platform for working around tight spaces and vehicles without that extra barrel length & barrel weight getting in the way, slowing the shooter down or bumping into things

M203 Enabled Rail System - The MK18 Rail Interface System (RIS II) features the Bolt-Up System has been rigorously tested prior to fielding by USSOCOM. If you can mount a M203 on the bottom of the the rail, the RIS II rail is the one to get

Plenty Of Mounting Space - The use of the traditional M1913 picatinny rail allows the user to mount tactical accessories on all four sides of the handguard to the exact position desired

Thick Government Profile Cold Hammer Forged Barrel - The A2 "Governmentprofile barrel was made with a greater thickness from the gas block forward to resist bending in the field and to allow a longer period of sustained fire without overheating. 

1:7 Twist Barrel Optimized For Heavier Bullet - The 1:7 twist rate is the most optimized for a 10.3" barrel for shooting standard 55 gr and up to 77 gr 5.56mm bullet for max velocity, stability and accuracy. (Generally heavier than 55 gr bullet is preferred when using a short barrel)

M&P 15 Sport II - Most Affordable

smith wesson mp15 sports 2
  • 7075 T6 Aluminum Upper & Lower
  • Polymer Handguard
  • Direct Impingement
  • Mil-Spec Standard trigger
  • 16" CHF Barrel
  • Mil-Spec buffer tube
  • 1/2" -28 Muzzle Thread Pitch
  • Type III Hard-Coat Anodized
  • 1:9 Barrel Twist
  • 6 Position Collapsible Stock

Why buy this one - The M&P 15 is a perfect entry-level AR15 without fancy accessories, and it's aimed at new AR buyers looking for a quality rifle at a bargain price.

The rifle also doesn't feature any aftermarket grips, stock or handguard, and it's a bare bone basic AR15 you can buy.

Of course the user can still upgrade this rifle from scratch by adding better rail handguard system, grips, stock, trigger and optic. Or the user can swap parts of the gun they don't like and the options are limitless.

Reliability wise, the M&P 15 performs just like any other AR15 without any hiccups because ultimately it's a AR without fancy accessories that don't affect the basic operation of the gun at all.

FN 15 - US Military Standard

FN15 military collector
  • 7075 T6 Aluminum Upper & Lower
  • Knights Armament M4 RAS Quad Rail
  • Ambi Selector
  • Direct Impingement
  • Mil-Spec Standard Trigger
  • 16" Button Broached Barrel
  • Mil-Spec buffer tube
  • 1/2" -28 Muzzle Thread Pitch
  • Type III Hard-Coat Anodized
  • 1:9 Barrel Twist
  • 6 Position Collapsible Stock & A2 Pistol Grip
Us army m4a1

Get this if you want what the military has - The FN15 is the civilian semi auto version of the military standard issue M4A1. The rifle is exactly same one issued to service members to all branches of the military. It's an awesome buy for buyers who value collecting historic military gears

UID-Labeled Lower - UID stands for Unique Identification, it's a label put on every US DOD production M4/M16 rifle to bring out the authenticity of this military collector series M4

Traditional Delta Ring Quad Rail - Unlike other fancy rail systems out there on the market today, the FN15 features the old school Knights Armament M4RAS Adapter rail with rail adapter covers

Standard A2 Style Front Sight Post - Old school A2 gas block front sight post for anyone who digs the original AR15 configuration

Included Ambidextrous Fire Selector - Right out of the box is ready for left & right handed shooters

16" Button Broached / Chrome Lined Barrel - Based on US military Technical Data Package, button barrel process allows FN to mass produce at about 30 seconds per barrel

Sig M400 TREAD

This is Sig Sauer's M&P Sport 2 offering. The rifle functions the same as any other AR15s, but comes with a lightweight MLOK rail system.

It has everything a new shooter needs right out of the box.

Smooth Trigger - Crisp single stage trigger control better than stock triggers in the past

Two Sided Mag Release - Easy to reach from either side of the grip to let go the empty mag

Ultra Slim Handguard - Light handguard reduces weight and provides firm grip on the rigid surface to reduce muzzle flip

LaRue Tactical Predator OBR - Best For Long Range

larue tactical predatorobr 16
  • 7075 T6 Aluminum Proprietary Upper
  • Direct Impingement (Adjustable For Suppressor Use)
  • LaRue Proprietary Robust Rail System
  • LaRue BMT trigger
  • Quick Detach 14.5", 16", 18" & 20" Barrel
  • Mil-Spec buffer tube
  • 1/2" -28 Muzzle Thread Pitch
  • Type III Hard-Coat Anodized
  • 1:8 Barrel Twist
  • LaRue A PEG Grip & 6 Position RAT Stock

Why LaRue Tactical ARs - The LaRue Tactical ARs stand out very much from the rest of the AR15 market. Yes! it's an AR15, but the rifle feels extremely solid, sturdy and durable for 0.25 MOA long range precision.

LaRue Tactical also is one of the top tier manufacturers for tight tolerance scope & accessories mounts used on high end firearms & ones contracted for the US military.

Solid Construction & Tight Tolerance - No wobble, Super tight tolerance & smooth bolt carrier action are the key elements that make the LaRue Predator OBR a great long range rifle

QD take down barrel

Referenced LaRue Tactical

Quick Release Barrel - The PredatOBR's barrel can easily be removed with the supplied PredatOBR Barrel Wrench, unscrew the Barrel Nut from Receiver and pull the Barrel Assembly free from Receiver. No need to remove the gas tube, gas block or muzzle device.

Suppressor Optimized - The PredatOBR's Port Selector Technology™ (PST) gas block is adjustable, to aid in the optimum function when using a sound suppressor to compensate for the extra blowback

Robust Rail System For Laser Accessories - The rail sections are CNC-machined from billet aluminum. This robust solution provides a perfect precision mounting space for aiming lasers, illumination and bipods.

PWS MK107 - Best Piston Driven SBR

MK107 Mod 1 M PWS rifle
  • 7075 T6 Aluminum Proprietary Upper
  • PWS M LOK 11" Handguard
  • PWS Triad 556 Muzzle
  • Radian Raptor Charging Handle
  • PWS Long Stroke Piston System (3 Adjustable Setting)
  • Mil-Spec Enhanced 5.5-6.5 lbs trigger
  • 7.75" 223 Wylde Barrel
  • Mil-Spec buffer tube
  • 1/2" -28 Muzzle Thread Pitch
  • Type III Hard-Coat Anodized
  • 1:8 Barrel Twist
  • BCM Retractable Stock & Grip
PWS piston driven MK107 upper in action

Referenced PWS, Look at that piston action!!

Pick PWS If Using Less Than 10" Barrel - For any AR pistol and SBR users who want the most reliable barrel system less than 10", the PWS piston-driven gas system is the best on the market for being reliable and durable.

The MK107 is the shortest available option in the MK1 MOD 1-M series, the MK107 was the first firearm developed by PWS. Known as “The Diablo”, the MK107 was designed to replace MP5 style weapons.

MK107 has been a vital part in the growing use of SBRs as patrol rifles.

No Heat Build Up On Bolt Carrier Group - Since piston driven system doesn't transfer hot gas to the bolt, the bolt remains cool and clean just like an AK

Increased Gas Volume For Better Piston Cycling - Optimized dwell time for a short barrel piston AR to cycle flawlessly and remains clean

Better Piston Gas Bleed Off - Improved gas bleed off valve allows the bolt carrier group to continuously function

Reduced Chamber Pressure - Increased bolt carrier mass to extend dwell time and delay unlock. As a result it allows less chamber pressure for easier extraction & increased durability of the bolt.

Cobalt Kinetics - Race Gun

cobalt kinetics BAMF
  • 7075 T6 Proprietary Mated Billet Receivers
  • Dual Drop Bolt Release
  • Full Ambi Control
  • Edge Muzzle Brake
  • Short Throw Safety Selector
  • 16" Cobalt EDGE Billet MLOK Handguard
  • AR GOLD Single Stage DMR Trigger
  • 16" 223 Wylde 4150 CMV steel Barrel
  • Cobalt Kinetics Pro Buffer System
  • 1/2" -28 Muzzle Thread Pitch
  • Type III Hard-Coat Anodized
  • 1:8 Barrel Twist

Why buy this space looking AR - For anyone looking for a non-standard AR15 with a unique look, feel, and operation, the Cobalt Kinetics AR15 will make you drop your jaw.

Besides the ultra unique external aesthetics, the gun ultimately functions like an AR15 but with couple innovative upgrades:

Auto Mag Drop On Last Round - Fast reload won't get any better than this. The bolt automatically locks open and the magazine automatically ejects on the last shot and it's ready for a new mag

Auto Bolt Release When Insert A New Magazine - The shooter can quickly insert the mag and get back on target without worry about the bolt catch. The shooter can insert a magazine into the gun with the bolt locked to the rear, then immediately chambers a round when the magazine is fully seated

Competition Speed Optimized - Super lightweight and streamlined 7075 T6 aluminum billet receiver design combined with carbon fiber parts right out of the box for anyone looking for a low drag performance AR

Adjustable Buffer System For Various Shooters - The performance of the rifle varies when shooting different types of ammo, and the Cobalt Kinetics buffer system allows the shooter to fine tune the gun to specific ammo type or suppressor use

Included American Gold Single Stage DMR Trigger - American Gold triggers are some of the best triggers on the market for short reset and crisp trigger pull that is great for speed and sub MOA precision

Geissele Super Duty - Sturdy Handguard

geissele super duty ar pistol

The Geissele Super Duty AR pistol has all the features of any other AR15s, and we put this on the list because it features the best barrel and handguard system out of the box.

SMR MK16 Rail - 10.5" top quality handguard with a super sturdy barrel nut locking system that keeps the barrel and handguard stiff 

Surefire Warcomp - Reduces recoil and muzzle flash all in one (Preinstalled)

Bomb Proof Gas Block - Ensures reliability under heavy use without getting loose

Rifle or Pistol - Available for 16" rifle or pistol variants 

ArmaLite was the first company that developed the AR-15 in the late 1950s for the military, then in 1959, the company sold the design to Colt.

In the 1960s Colt started to manufacture the automatic rifle that soon became standard issue for U.S. troops in the Vietnam War. It was known as the M-16.

Later, Colt ramped up production and started selling the rifle to law enforcement and the civilian market as the AR-15.

When Colt's patents for the AR-15 expired in the 1970s, other manufacturers began making similar models.

By now the AR15 type rifles have gone though so many upgrades to improve modularity, performance and ergonomics.

Gas System

The AR15 has two gas systems:

  • Direct Impingement (DI)
  • Piston Driven

If this is your first time buying an reliable AR15, please go for a direct impingement gas system 7" or more. Generally these are standard 16" long barrel rifles with the most balanced components for reliable use.

The Stoner DI design is the most common, which involves redirecting the hot gas leaving the barrel back into the gun to recycle the bolt carrier group via the gas tube.

While the direct impingement system can be very reliable, there is no doubt that a lot of fouling can build up on the bolt carrier group.

There are 4 major DI gas system lengths:

  • Pistol 4"
  • Carbine 7"
  • Mid Length 9"
  • Rifle Length 12"

The Piston Driven design uses the propellant gas to operate a rod that acts as an intermediary to exert force on the bolt carrier group to cycle the weapon.

All excess gas is bled out of the gun well forward of the receiver. This helps keep the guns extremely clean. Ultimately it's just like how an AK47 operates.


The AR15 platform has evolved over time. Now the AR15 can be chambered in these most popular centerfire cartridges besides 223/5.56:

  • 6.5 Grendel
  • 300 BLK
  • 22 Nosler
  • 450 Bushmaster
  • 458 SOCOM
  • 350 Legend (See 350 Legend upper)
  • 50 Beowulf
  • and more...


zeroing mk18 elcan specterdr

Most AR15s are durable, but there are couple key areas a buyer should pay attention to for more durability.

  • Features Staked Castle Nut Ring ?
  • Features Anti Rotational Handguard Locking Mechanism ? Prevents the handguard from getting loose
  • Features Forward Assist ? Helps seat the bolt & clear malfunction
  • Features Anti Rotational Trigger Pins? Prevents the trigger pins from popping out of the receiver

Bolt Carrier Group

aero precision bcg nickel boron

The bolt carrier group (BCG) is one of the core components of the rifle that holds the hammer, striker pin, extractor, gas key & the rotating bolt.

Most ARs you find on the market today will ship with full auto M16 bolt carrier group.

There are differences between an AR-15 and M-16 bolt carrier group. The fully automatic M-16’s bolt carrier group has more material on the back, for starters, allowing compatibility with a fully automatic sear.

Must be tought built - Because of the BCG experiences powerful forces, it is important that no weaknesses exist in the metal. In order to ensure that, the makers of your BCG put their products through a battery of tests.

Look for MPI rated BCG - These tests include magnetic particle inspection and high-pressure testing. Magnetic particle inspection ensures that there are no breaks or cracks in the metal the bolt carrier is made of.

Manganese Phosphate (Most Common) - Its benefits are that it’s economical, durable, and corrosion-resistant but, due to its highly porous nature, it is also difficult to clean. 

Chrome - Chrome is both harder and more porous, both of which make it easier to clean. Unfortunately, it is expensive and brittle.

Nitride - Nitride is a chemical treatment that results in a hardened black surface. It is durable and highly corrosion resistant. However, if it is not done properly, it can have a negative effect on the sensitive part of the bolt carrier group. 

Electroless Nickel (Smoothest action) Electroless nickel results in a thin surface layer that is harder than the underlying metal. It has excellent lubrication properties. While easy to clean and less reliant on lubrication, however, the coating can wear off over time. 

Upper Receivers [Core Components]

radian weapon system mod 1 upper

The upper receiver hosts the barrel assembly, optic, sights, charging handle and the bolt carrier group.

The A2 style upper receiver is the most common, meanwhile custom / cool looking billet upper receivers are available too if you want something unique.

Who makes them ? The upper receiver forgings are all essentially the same, they simply come from different forging machine shops.

So quality and tolerance do vary. You can identify which forging shop your receiver is made from by looking at the stamp.

The most common two are:

  • ‘Keyhole’ (Cerro Forge) 
  • ‘Square’ (Brass Aluminum Forging Enterprises)
ar15 receiver stamps

but you will see more if you keep looking.

What's cool is that you can put on other upper receivers for different applications and looks later down the road. Check out more complete upper receivers here.

Lower Receivers [Core Components]

The lower receivers host the trigger group, pistol grip, spring system, stock, magwell, mag release and upper receiver retainer pins.

The main receiver is considered a firearm, which requires FFL when purchasing. People can buy a complete lower or build it piece by peice.

There are tons of accessories available on the market for it as well.

Accessories [Attachments, Grips & Stocks]

ar15 accessories

This part is self explanatory, and they improve the handling and ergonomics of the rifle, but not the basic operation of the rifle. Please check out our links below:

Best AR15 Handguards

Best AR15 Accessories

Best Red Dot Sights


hrf dual ramp modbutton laser and surefire plug angled

The handguard is what fundamentally makes the AR15 more tactical looking & configurable, and one of it's major usage is to provide additional mounting space for accessories.

Currently the most popular handguard mounting systems are:

Instead of having a hand guard with a picatinny rail attached, the KeyMod & MLOK were designed so that accessories could be mounted directly onto the rail. This also allows for picatinny rails to be mounted onto the handguard wherever needed.

dd mk18 handguard with hotbutton setup

A sturdy and tight tolerance CNC machined handguard is important to secure any laser devices for zero retention.

A good handguard system consists of the following:

  • Rock solid barrel nut
  • Anti rotational handguard tab that hold on to the upper receiver
  • Handguard should be bolted onto the barrel nut (No friction clamp)
  • Aligns with flat top receiver
  • Enough mounting locations for accessories

Barrel [Twist Rate, Length & Lining]

ar15 barrel 16 inches

There are tons of AR15 barrel options on the market today. Different material, lengths, profile and twist rate can affect the ballistic performance.

Overall, Cold Hammer Forged barrels are the most durable with the longest service life on the market.

Every barrel has the rifling groove inside, and the twist rate is represented as follows:

1:8 means 1 bullet revolution for every 8"

1:7 means 1 bullet revolution for every 7"

This will affect the bullet speed and stability when exiting the barrel. The shorter the barrel, the tighter the groove spiral.

As far as twist rate goes, this chart best explains which twist rate barrel is best for a specific 5.56/223 bullet grain

AR15 twist rate barrel chart



Most out of the box AR15 will have standard mil-spec single stage trigger with about a 9 lb trigger pull.

The user can swap out the factory trigger with an aftermarket trigger at any time to improve overall performance of the rifle.

An upgraded trigger pack generally reduces the trigger pull weight significantly down to 2 - 5 lbs , which gives the shooter super smooth trigger action for fast follow up shooting or better precision shots.

Full Auto Trigger - Only available for legal registered NFA full auto AR15, Hard to find or buy for most people

Single Stage - Recommended for high speed competition shooting. No pre-travel, short reset & crisp trigger break

2-Stage Trigger - Recommended for long range shooting, where it gives the shooter less finger tension on the trigger prior to the steady trigger break as light as 2.5 lb

Muzzle Device


A muzzle device can minimize muzzle fireball, counter recoil & reduce unwanted muzzle rise.

All AR15 muzzle devices are standard 1/2" -28 thread pitched. The most standard is the A2 birdcage flash hider with the main purpose to reduce muzle fireball signature.

In order to reduce recoil & muzzle rise, the user can buy various muzzle brakes & compensators. These have specifically shaped ports and chambers machined into the muzzle device to redirect the hot gas as soon as the bullet leaves the barrel to minimize muzzle drift, climb & recoil.

Gas Block

gas tube and gas block

For a direct impingement system, the gas block holds the gas tube in place. As long as the gas block fits the barrel and clears the handguard, then you're good to go.

There are three different gas block diameter specs:

  • 75″
  • 825″
  • 0.936"

0. 75″ is the most common size, but always measure the barrel if you aren't sure while doing custom upgrades or build

The gas block quality and the size of the gas port must be carefully matched to give the rifle the best performance for cycling and when using a suppressor.

To go a step further, an adjustable gas block is recommended for managing the gas performance based on ammunition types and the use of a suppressor.

Buffer Tube


The buffer tube retains the buffer and the buffer spring, and the butt stock slides on it.

Most buffer tubes are machined with 6 position slots for having a retractable stock, but there are two buffer tube sizes:

  • Commerical (1.170" diameter)
  • Mil-Spec (1.14" diameter)

They don't havy any signification functional difference, but Mil Spec stock can't fit on a commerical tube.

To see their in-depth dimension difference, please click here.

Charging Handle

vortex micro 3x qd mount on top rail

Most AR15 comes with a standard left-handed charging handle with a small latch, but you can replace it with an Ambi charging handle featuring a larger latch for more leverage & more gripping room.

It makes charging the bolt & clearing jams so much easier.