One Shooters’ Forum member asked: “What makes an AR accurate? What parts on an AR can really affect accuracy — such as free-floating handguards, barrels, bolts, bolt carriers?” He wanted an honest, well-informed answer, not just sales pitches. Robert Whitley posted a very detailed answer to this question, based on his experience building/testing scores of AR-platform rifles. Robert operated AR-X Enterprises, which produced match-grade uppers for High Power competitors, tactical shooters, and varminters.
Building an Accurate AR — What is Most Important
by Robert Whitley
There are a lot of things that can be done to an AR to enhance consistent accuracy, and I use the words “consistent accuracy” because consistency is a part of it (i.e. plenty of guns will give a couple great 5-shot groups, but won’t do a very good 10- or 20-shot groups, and some guns will shoot great one day and not so good on others).
Here are 14 key things we think are important to accuracy.
1. Great Barrel: You’ll want a premium match-grade barrel, well-machined with a good crown and a match-type chambering, true to the bore and well cut. The extension threads must also be cut true to the bore, with everything true and in proper alignment.
2. Rigid Upper: A rigid, heavy-walled upper receiver aids accuracy. The typical AR upper receiver was made for a lightweight carry rifle and they stripped all the metal they could off it to make it light to carry (which is advantageous for the military). The net result are upper receivers that are so thin you can flex them with your bare hands. These flexible uppers are “strong enough” for general use, but they are not ideal for accuracy. Accuracy improves with a more rigid upper receiver.
3. True Receiver Face: We’ve found that truing the receiver face is valuable. Some may argue this point but it is always best to keep everything related to the barrel and the bore in complete alignment with the bore (i.e. barrel extension, bolt, upper receiver, carrier, etc.).
4. Barrel Extension: You should Loctite or glue the barrel extension into the upper receiver. This holds it in place all the way front to back in the upper receiver. Otherwise if there is any play (and there typically is) it just hangs on the face of the upper receiver completely dependent on the face of the upper receiver as the sole source of support for the barrel as opposed to being made more an integral part of the upper receiver by being glued-in.
5. Gas Block: You want a gas block that does not impose pointed stress on the barrel. Clamp-on types that grab all the way around the barrel are excellent. The blocks that are pinned on with tapered pins that wedge against the barrel or the slip on type of block with set screws that push up from underneath (or directly on the barrel) can deform the bore inside of the barrel and can wreck the accuracy of an otherwise great barrel.
6. Free-Float Handguard: A rigid, free-float handguard (and I emphasize the word rigid) really makes a difference. There are many types of free-float handguards and a free-float handguard is, in and of itself, a huge improvement over a non-free-float set up, but best is a rigid set-up. Some of the ones on the market are small diameter, thin and/or flexible and if you are shooting off any type of rest, bipod, front bag, etc., a rigid fore-end is best since ARs want to jump, bounce and twist when you let a shot go, as the carrier starts to begin its cycle before the bullet exits the bore.
7. Barrel Contour: You want some meat on the barrel. Between the upper receiver and the gas block don’t go real thin with a barrel (we like 1″ diameter if it’s workable weight-wise). When you touch off a round and the bullet passes the gas port, the gas system immediately starts pressuring up with a gas impulse that provides vibrations and stress on the barrel, especially between the gas block back to the receiver. A heavier barrel here dampens that. Staying a little heavier with barrel contour through the gas block area and out to the muzzle is good for the same reasons. ARs have a lot going on when you touch off a round and the gas system pressures up and the carrier starts moving (all before the bullet exits the bore) so the more things are made heavier and rigid to counteract that the better — within reason (I’m not advocating a 12-lb barrel).
8. Gas Tube Routing Clearance: You want a gas tube that runs freely through the barrel nut, through the front of the upper receiver, and through the gas key in the carrier. Ensure the gas tube is not impinged by any of them, so that it does not load the carrier in a stressed orientation. You don’t want the gas tube bound up so that when the gas tube pressures up it immediately wants to transmit more force and impulse to the barrel than would normally occur. We sometimes spend a lot of time moving the gas block with gas tube on and off new build uppers and tweaking gas tubes to get proper clearance and alignment. Most gas tubes do need a little “tweaking” to get them right — factory tubes may work OK but they typically do not function optimally without hand-fitting.
9. Gas Port Tuning: You want to avoid over-porting the gas port. Being over-gassed makes the gas system pressure up earlier and more aggressively. This causes more impulse, and increases forces and vibration affecting the top end and the barrel. Tune the gas port to give the amount of pressure needed to function properly and adequately but no more.
10. Front/Back Bolt Play: If accuracy is the game, don’t leave a lot of front/back bolt play (keep it .003″ but no more than .005″). We’ve seen factory rifles run .012″ to .015″ play, which is OK if you need to leave room for dirt and grime in a military application. However, that amount of play is not ideal for a high-accuracy AR build. A lot of front/back bolt play allows rounds to be hammered into the chamber and actually re-formed in a non-consistent way, as they are loaded into the chamber.
11. Component Quality: Use good parts from a reputable source and be wary of “gun show specials”. All parts are NOT the same. Some are good, some are not so good, and some aftermarket parts are simply bad. Don’t be afraid to use mil-spec-type carriers; by and large they are excellent for an accuracy build. Also, remember that just because a carrier says “National Match” or something else on it does not necessarily mean it’s any better. Be wary of chrome-plated parts as the chrome plating can change the parts dimensionally and can also make it hard to do hand-fitting for fit and function.
12. Upper to Lower Fit: A good upper/lower fit is helpful. For quick and dirty fit enhancement, an Accu-Wedge in the rear helps a lot. The ultimate solution is to bed the upper to a specific lower so that the upper and lower, when together, are more like one integral unit. For the upper receivers we produce, we try to get the specs as close as we can, but still fit the various lowers in the market place.
13. Muzzle Attachments: Don’t screw up the muzzle (literally). Leave as much metal on the barrel at the muzzle as you can. People like to thread the muzzle for a flash hider, suppressor, muzzle brake, or some other attachment, but if you really want accuracy, leave as much metal as you can there. And, if you have something that screws on, set it up so that it can be put on and have it stay there without putting a lot of torque and stress on it right where the bullet exits the bore. If you are going to thread the end of the barrel, make it concentric with the bore and make sure what you screw on there is as well. For all muzzle attachments, also ensure that the holes through which the bullet passes through are dead true to the bore. Many aftermarket screw-on things are not so good that way. Anything that vents gas should vent symmetrically (i.e. if it vents left, it should vent equally right, and likewise, if it vents up, it should vent down equally). Uneven venting of gas can wreck accuracy.
14. Quality Ammunition: Ammo is a whole story by itself, but loads that are too hot typically shoot poorly in an AR-15. If you want accuracy out of an AR-15, avoid overly hot loads. Shown below are test groups shot with four (4) different uppers, all with moderate loads. These four uppers all pretty much had the same features and things done to them as explained in this article, and they all shot great.
Robert Whitley
6mmAR.com
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There are many tactical-style video producers on YouTube. Many of these guys, to be honest, aren’t very knowledgeable about firearms, nor are they particularly good shooters. By contrast, videos hosted by Tactical Hyve regularly feature top Action Pistol, PRS and 3-gun competitors as well as military SPECOPS veterans. The vets include SEAL team members who really know their stuff. The Tactical Hyve YouTube channel currently hosts over 560 videos! Here are seven of our favorite Tactical Hyve videos featuring highly-skilled instructors.
1. How to Aim a Pistol with Iron Sights or Red Dot
We recommend this video for persons training for a CCW permit, or who are getting started in pistol shooting competition. The video shows proper technique for using iron sights. In addition, it offers some important advice for shooting with Red Dots. Shooting with Red Dot sights can be easier than with iron sights because you only have to put the dot on the target, rather than align front blade with rear notch. But it does take some familiarization to get things right. And persons with astigmatism can have challenges with Red Dot sights.
2. Five Most Common Pistol Shooting Mistakes
In this video, Myles, the founder of Tactical Hyve, talks about the five most common pistol shooting mistakes he sees in classes and how to correct them. Many folks begin pistol shooting without a qualified instructor. Or they try to imitate what they see on TV. This can lead to new pistol shooters forming bad habits. This video helps handgunners correct those bad habits. This popular video has 1.9 million views.
3. Dry-Fire Techniques with Pistol Master Champion J.J. Ricaza
Released on 8/4/22, this is the latest video from the Tactical Hyve YouTube channel. The featured shooter, J.J. Ricaza, a multi-time Steel Challenge champion, is one of the top 10 action pistol shooters in the country. Racaza show how to dry fire like a grandmaster in this video. Dry-firing lets you polish your technique at home, and improve your skills without the cost of live ammunition.
4. Reticle Types Reviewed — MOA and MilRAD
In this video, Billy Leahy, former USCG Precision Marksmanship Instructor, talks about the common optics reticles you’ll encounter. This is a good video to watch if you are shopping for a new scope and are considering a variety of reticle types, both MilRAD (Milliradian) and MOA, SFP and FFP. In this video, Leahy covers the following reticles:
Standard Mil Dot
Leupold TMR
Nightforce Mil-XT
Horus Tremor3
Vortex EBR-7C (MRAD)
Vortex EBR-2C (MRAD)
Vortex EBR-4 (MOA)
5. Use of Tripods for Precision Rifle Competitions
In this video, retired Green Beret and nationally-ranked precision rifle shooter, Scott Satterlee, shares precision rifle tripod shooting tips. This is a “must-watch” video for PRS/NRL shooters who may use tripods in competition. This video can also benefit hunters who might use a tripod in the field.
6. Pistol and Rifle Methods for CROSS-Dominant Shooters
What is “Cross Dominance” and how do you adjust for it? Those questions are answered in this video. If your dominant eye is opposite your dominant hand, then you are cross-dominant. For example, this Editor is right-handed but my LEFT eye is dominant. So I am cross-dominant. This video starts with a simple exercise to determine your dominant eye. Then the video shows how to hold a pistol correctly if you are cross-dominant. Finally, the video shows techniques that benefit cross-dominant rifle shooters.
7. Setting Up an AR-15 for Home Defense
In this video, retired Navy SEAL Mark “Coch” Cochiolo shares how his primary AR for home defense is set up. Coch reviews various optics choices and he also explains how to mount a lamp on your home defense rifle(s). The AR-15 set-ups of ten other tactical experts are revealed in a Tactical Hyve web article. See:
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Ever wondered how the parts inside an AR15 work together? Just exactly how does the reciprocating bolt carrier feed rounds from the magazine? How do the elements in the trigger group work and reset after each shot? How does the gas system bleed gas from the barrel and operate the bolt carrier? These and other questions are answered in this eye-opening video from 45Snipers. Using “cutaway” 3D computer animation, this 5-minute video shows all features of an AR15 inside and out. This fascinating firearms animation allows the viewer to look inside the upper and lower receivers, into the bolt carrier, chamber, barrel, and magazine.
This video starts off slow and has annoying background music, but it is well worth watching if you own or shoot any AR-platform rifle. It illustrates all the key operations during the charging, loading, firing, and ejection processes. The cutaway animation shows how rounds are stripped from the magazine and then chambered. It then shows how every part of the trigger group works, and how the firing pin strikes the primer. You can even watch the bullet move down the barrel before the empty shell casing is removed from the chamber and tossed out the ejection port. Here are sample frames from the video:
Video find by Grant Ubl. We welcome reader submissions.
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AR-platform rifles can be maintenance-intensive beasts. But some AR owners make the situation worse by not regularly cleaning important small parts, or by using too much oily/greasy lubricants in the wrong places. A properly maintained and lubricated AR15 can shoot hundreds of rounds (between cleanings) without a problem. If you learn where (and where not) to apply lubricant, you’ll find that your AR will run more reliably and the task of cleaning the bolt and bolt carrier will be less of a burden.
Here is a good video that explains AR-15 Cleaning and Maintenance. In this 30-minute NSSF video, Gunsite Academy instructor and gunsmith Cory Trapp discusses the proper way to clean and maintain the AR-15 carbine. Very knowledgeable, Trapp provides rock-solid advice for AR owners. Along with cleaning procedures, this video explains how to inspect key components and how to function-test your AR before each shooting session.
If you want to keep your black rifle running smoothly and reliably, you must clean it regularly and follow the correct maintenance procedures. Here’s another good video that explains how to properly disassemble and clean AR-platform rifles.
Take-Down and Full Cleaning of AR15 by Jerry Miculek
Here ace shooter Jerry Miculek takes down and cleans an AR-platform rifle belonging to his daughter Lena. This is a good video because Lena’s rifle was “run hard and packed up dirty” so you can see where carbon and grease build up. This 35-minute video is very thorough. Jerry is one of the nation’s top action carbine shooters, so listen carefully to his advice on cleaning and lubrication.
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409,000,000 views! Today’s five feature videos have, collectively, been viewed 372 million times on YouTube. Today’s Saturday special features five remarkable animated firearms videos from Matt Rittman, a very talented computer graphic artist. Matt employs multiple software programs to create these incredibly detailed animations. His software tools of the trade include Cinema 4D, Substance Painter, and Corona renderer. Don’t think this is easy. Some of these videos took over 500 man-hours to create. Enjoy!
AR-15 Full Animation — Components and Function
While there are other AR-15 animations on YouTube, we think this is the most accurate and creative, showing the function of a wide variety of components, including the bolt carrier, extractor, trigger, stock buffer, safety system, forward assist, and mag release. It also shows modes of a military M16, showing 3-round burst fire, and full-auto, employing disconnectors and auto sear. If you are planning to assemble/disassemble an AR, this is definitely worth watching start to finish. This video has recorded over 2 million views in just three weeks!
4:00 Auto Fire
4:58 Burst Fire
6:22 Bolt Catch
6:40 Sights
7:33 Adjustable Stock
7:50 Ejection Port Cover
Mauser Kar-98K Bolt Action Rifle video
This elaborate 3D animation shows how a Mauser-type Karabiner 98 Kurz (aka Kar-98K) bolt-action rifle works. Substance Painter was used to create the wood stock texture. Creator Matt Rittman states that this 3.7 minute video took over 500 man-hours to create. You have to admire the dedication involved in that kind of hard work.
This 3D animation video shows the popular Glock 19 (Gen 4) pistol. This modern, polymer-framed, striker-fired pistol has constant trigger pull for all shots. Some folks call this a DAO (double-action-only) trigger but that’s not really correct. Unlike the Model 1911, on a Glock there is no external safety on the frame or slide. The trigger “shoe” (the part that contacts finger) includes a central blade. This prevents the gun from firing unless the trigger is depresses normally. Glock calls this the “safe action”. The creator, Matt Rittman states: “Cinema 4D was used to create each individual part, as well as animating everything. Substance Painter was used to create the main textures. Corona renderer was used to render everything. This animation [with 84.6 million views] took me over 500 hours to create.”
Elements of Video:
0:11 Basic Function
0:39 Case Extraction
0:47 Cartridge Loading
1:02 Trigger Reset
1:28 Trigger Safety
Pump shotguns are essential firearms for hunting and home defense. The clever design of pump-action shotguns make them reliable even when feeding large diameter, blunt-ended 12 gauge shot-shells.
With 233 million views, this AK-47 video might just be the most-watched firearms tech video on YouTube. The video highlights the design features the account for the AK’s legendary reliability. For viewers with an eye to detail Matt adds this clarification: “The firing pin does NOT puncture the bullet primer. It just strikes it against the anvil, initiating the firing sequence.”
AR owners know that their black rifles require regular cleaning and maintenance. And this modular platform allows many options for stocks, fore-arms, and optics mounting. That ability to customize is one of the AR’s major attractions, but customization requires solid understanding of the AR’s design and components.
To help AR owners optimize and maintain their rifles, Gun Digest Media has a 320-page illustrated book: AR-15 Setup, Maintenance and Repair. Authored by Patrick Sweeney, this paperback book is a “one-stop guide to repairing, maintaining and modifying America’s favorite rifle.” The current price for the book is $29.99 from Gun Digest, or $32.34 on Amazon. Gun Digest also offers a $29.99 Digital Download version.
GET FREE 40-Page AR-15 Book Sample
Note, if you are interested in the book, there is a substantial 40+ page FREE sample available on the Amazon site. You can see the entirety of the first two chapters from the Kindle digital version. CLICK HERE to visit Amazon.com and then click on the button labeled “Read Sample” below the cover image.
AR Set-Up and Maintenance
If you need to disassemble and maintain your AR rifle, swap barrels or handguards, add optics, or customize the stock, Gun Digest’s AR-15 Setup, Maintenance and Repair book tells you what you need to know. From field-stripping to barrel mounting and trigger installations, the book covers a wide range of topics. The book provides step-by-step instructions for set-up and maintenance, with hundreds of detailed photos. The book also includes AR gunsmithing chapters with reviews of recommended tools.
Author Patrick Sweeney is a certified master gunsmith and armorer instructor for police departments. Sweeney has also authored the notable 4-volume Gunsmithing the AR-15 series (Vol. 1, Vol. 2, Vol. 3, and Vol. 4) and 20+ other titles for Gun Digest Books.
Whether you want to learn about disassembling your AR for regular maintenance, field-stripping, swapping out parts, adding optics or customizing a stock, AR-15 Setup, Maintenance and Repair guides you through everything you need to know to keep your AR-platform rifle running well. There are also tips on how to improve accuracy, and maintain your bolt carrier group properly.
Authored by Patrick Sweeney
Published by Gun Digest Books
ISBN-13: 978-1951115470
320 pages, softcover, 8 ¼ x 10 7/8 inches
Editor’s NOTE: The key to keeping an AR running reliably is proper lubrication (in the RIGHT places), and regular cleaning of the bolt carrier and bolt, including ejector recess and extractor recess. The majority of non-functioning ARs we’ve seen had gunk, lube, carbon, and brass shavings in those recesses.
Other AR Books by Patrick Sweeney
Bonus Video — AR15 Maintenance with Jerry Miculek
In this helpful video, legendary shooting Jerry Miculek explains how he cleans and maintains his AR-platform rifles. Miculek shoots ARs in three-gun competitions.
Do you own or shoot an AR-platform “black rifle”? Then you know these rifles run dirty, and have some unusual maintenance requirements. On the other hand, the AR “Modern Sporting Rifle” is fun and versatile with a vast range of options among buttstocks, barrels, handguards, and grips. You can assemble a simple 16″ barrel .223 Rem rig for home defense, or build a long-barreled 6mm ARC rifle with bag-rider buttstock and high-magnification optic for long range target work. The choice is up to you.
To help with your black rifle journey, here are eight helpful videos from Brownells. These will help ensure your AR rifle cycles reliably and runs longer, with reduced wear. Brownells also explains how to choose the optimal barrel twist rate. CLICK HERE to order AR parts, accessories, and ammo from Brownells.
AR Bolt/Bolt Carrier Lubrication — Smarter Methods
This video shows the proper way to lubricate an AR-15 bolt-carrier assembly. The video identifies the key metal-on-metal friction points where you actually need lubrication: the rails on the underside of the carrier, shiny wear points on top, and just a dab on the cam pin. How much oil/lubricant should you use? The AR-15 is pretty forgiving on that point. Some spots work best with grease, others work best with a lighter oil. Just keep it out of the combustion areas. Those little holes in the carrier are gas vent holes, NOT oil holes!
AR Maintenance — General Cleaning Procedures
Let’s face it, ARs with the original gas system tend to run dirty. You’ll need to regularly clean the bolt carrier and bolt. In addition you should regularly clean the chamber area and the inside of the upper. Also make sure to clean the lower (see video 3:15) and ensure the trigger assembly is properly maintained. This video covers general cleaning and maintenance of AR-platform rifles. We highly recommend that all new AR owners watch this video. NOTE: When cleaning the bolt, don’t forget the extractor recess and ejector recess. The majority of ARs we’ve seen that did not function properly had gunk (lube, carbon, brass shavings) clogging these areas.
AR Barrel Twist Rates — What You Need to Know
AR barrels can be ordered with a variety of twist rates from 1:12″ to 1:7″. Basically, the longer/heavier the bullet you plan to shoot, the faster the twist rate you need. For example, Sierra recommends a 1:7″ twist rate for the 90gr SMK. A 1:12″ could work with the small lightweight bullets up to 55 grains. The 1:9″ barrel will stabilize the light and mid-weight bullets up to about 77 grains. We recommend a 1:8″ or 1:7″ twist rate for the best versatility. You’ll find a detailed discussion of AR twist rates on PewPewTactical.com.
How to Install an AR15 Trigger Assembly
One of the most common AR upgrades done by black rifle owners is swapping out the trigger for a better unit (perhaps a two-stage). Trigger replacements on ARs can be done fairly easily with basic tools. But there are some recommended procedures to ensure the trigger group swap goes easily. You’ll want to have a proper mount to secure the lower, and tools that fit the pin diameters on your lower.
AR Rifle Build — How to Avoid Common Mistakes
This Brownells video explains five common yet serious errors people make while assembling or modifying AR-15 class rifles. Here are the five mistakes all AR builders need to avoid:
1. Mounting Accessories that Contact the Gas Block: A common mistake is attaching accessories like bipods directly to the handguard in such a way that screws exert pressure on the gas block. This misalignment can harm accuracy. The solution involves carefully selecting the attachment point or opting for shorter screws.
2. Incorrect alignment of the Gas Block: This is another widespread issue. Properly aligning the gas block with the barrel’s gas port is essential for the rifle’s reliable operation. Misalignment can lead to cycling problems due to insufficient gas flow.
3. Over-Torquing the Castle Nut: Applying excessive torque to the castle nut can damage the threads of the receiver extension, also known as the buffer tube. The recommended torque setting is 40 foot-pounds. Exceeding this value can compromise the structural integrity of these components.
4. Excessive Material Removal in Upper Receiver Lapping: Removing too much material when lapping the upper receiver, can cause the barrel to sit too far into the upper receiver. This misplacement can affect feed ramp alignment and gas block positioning, potentially leading to functional issues.
5. Improper Buffer Tube Installation: Failing to install the buffer retainer and spring correctly, or screwing the buffer tube in excessively, can obstruct the upper receiver’s closure. Correct installation depth is crucial for these components to perform their intended functions.
Checking Headspace on ARs
In this Tech Tip, Brownells gun tech Steve Ostrem walks users step-by-step through the process of checking headspace on their AR-15 rifles, both new and used. It is very important to have proper headspace to ensure proper feeding and extraction, and to ensure good brass longevity (with less risk of dangerous case separation). Starting at 2:10, this video explains how to check headspace with go/no-go gauges and maximum headspace gauge. Ostrem notes: “If you have an AR that closes on a no-go gauge, we recommend taking it to a gunsmith before heading to the range.”
Excessive headspace in AR platform rifles can lead to dangerous case separation.
Setting Up Gas Tube Systems
This Tech Tip examines AR-platform gas systems, and shows how to select the proper length gas tube, and how to configure multiple tube systems if you change your barrel to different lengths. This is worth watching for anyone re-barreling an AR.
Barrel Gas Block Alignment — Key to Reliable Cycling
In this video, Brownells gun tech Steve Ostrem explains surefire methods to align your gas block. The most common problem with AR builds is poor cycling, commonly caused by misalignment between the gas block and the barrel’s gas port.
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Retro is back — at least in the CMP’s Standard Modern Military Rifle AR class. Though Service Rifle competition has evolved to allow optics and heavy barrel profiles, the Standard Modern Military Rifle (AR category) is truly a “blast from the past”. Overall weight is limited to 7.5 pounds, and the rifle must be equipped with iron sights (Rule 5.2.3). In addition, the rifle must “be based on the M-16 rifle or be based on an AR design” with “exterior configuration similar [to] the original military or military-type rifle”. See Rules.
With this in mind our friend Dennis Santiago has put together his own AR-platform Standard Modern Military Rifle for matches run under CMP Games Competition Rules. This is not quite a classic AR, as it has a metal free-float handguard (vs. plastic handguards), but it IS light (7.3 pounds), and it does have iron sights — a key requirement for Standard Modern Military class rifles. CMP Rulebooks — All Classes.
Here is Santiago’s CMP Modern Military Rifle (Standard Class) with an ultralight free float tube that has a titanium barrel nut, and mechanical, center-able front sight. The barrel is an AR-Stoner brand 20″-long 1:7″ Government contour chambered in 5.56×45 NATO. Dennis says: “This makes the 7.5-lb weight limit with a few ounces to spare. We’ll see how well it drives soon enough.”
Dennis explains: “The Standard Modern Military (AR) is a category of military-style rifle that shoots the 200-yard, 30- or 50-shot courses alongside the M1 Garands, Springfields, Vintage, and M1 Carbines. This one boasts a Midwest Industries (MI) ultralight Free-float Handguard and a Yankee Hill folding front sight. Any Government contour or thinner profile rifle-length gas tube barrel with a 0.750″ gas block will work.” Colt makes a suitable Government Contour 20″-long, 1:7″-twist barrel, sold by MidwayUSA.
To test the accuracy of his rifle, Dennis fitted a Mantis-X unit on the top of the float tube. The Mantis-X records the movement of the rifle to interpolate shot placements. Dennis reports: “I spent some extra time at the range grabbing a decent zero for my Modern Military rifle. I stuck a Mantis-X on it to record a few shots shooting offhand at the plates at 200 yards. It drives very easily even with no shooting coat or glove.” The Mantis-X is attached just forward of the carry handle, on top of the MI free-float handguard. The Mantis-X works with live fire as well as dry fire. It communicates via BlueTooth to a smartphone App.
Rifle Shoots Well with 77gr Sierra MatchKings
The gun is presently zeroed with 77gr Sierra MatchKing ammunition. Dennis reports his rifle “can easily hold the X-Ring on an SR target for both 100-yard and 200-yard CMP Modern Military Games matches. And it’s fun to shoot!”
CMP Standard Modern Military Rifle (AR Class)
This rifle is built from carefully selected and fitted parts to conform to the CMP’s 7.5-pound weight limit iron-sighted rifle rule. Officially, this is a CMP Standard Modern Military Rifle, Class “A” (AR type).
1. S&W M&P lower receiver
2. White Oak Armament match upper receiver with 1/4×1/4-MOA pinned rear sights
3. AR-Stoner 20″ 1:7″-twist 5.56x45mm NATO Government contour barrel from MidwayUSA*
4. MidWest Industries ultralight free-float handguard with a Titanium barrel nut
5. Yankee Hill Machine folding front sight with a 0.072″ square front pin
6. RRA 2-stage trigger
7. A2 length buttstock
Easy Rifle Build Using Mostly Existing AR Parts, Plus New Barrel and Free-Float Handguard
Dennis was able to put his Modern Military AR together using components he had collected over the years: “Most of these parts were already in my bin of old AR parts available to be recycled. The barrel and free-float handguard were the only new acquisitions.” And with the AR’s modular format, this was an easy build: “Assembly time was about 30 minutes. I’ve done these parts swaps so many times now.”
Key Rules for Standard Modern Military Rifle (AR Type)
Dennis Santiago’s new AR rifle was built as a “Standard U.S. Modern Military Rifle”, Class A (AR Type), as specified in the CMP Games Competition Rules.
5.2.3 Standard U.S. Modern Military Rifles, Class A
Category A Standard Modern Military Rifles must comply with these requirements:
a) Rifles must be based on the M-16 rifle or be based on an AR design;
b) Rifles must be manufactured by a USA manufacturer;
c) Rifles must be equipped with issue-type metallic front and rear sights; rear sights with adjustments finer than one minute of angle are permitted;
d) Total rifle weight, with sights and without sling, may not exceed 7.5 pounds;
e) Rifles may be fitted with a float tube or free-floating handguard. A nonadjustable sling swivel may be attached to the forward end of the handguard; and…
f) The rifle must be chambered for the 5.56x45mm or .223 Remington cartridge.
Also, from Rule 5.2.2:
a) The exterior configuration of the rifle must be the similar to that of the
original military or military-type rifle;
b) The trigger pull may not be less than 4.5 lbs.;
Comments from other Modern Military Rifle Shooters:
“I built a Modern Military [Standard]. It was tough getting below the 7.5-lb [limit]. I had to carve off a bunch of the 20″ barrel diameter but wanted to stay with it for sight radius (over a 16″). I would just as soon shoot that little iron-sighted rifle at 200 yards as my 15-lb Nightforce-scoped Service Rifle. I love that little rifle.” — Kenneth S.
“I’m building one of these that will make 7.5-lb [Standard Modern Military] weight limit, with the long barrel and long sight radius. This has been on my list this winter.” — Tom K.
“We found that turning down a National Match barrel and taking a few inches off of it made a very accurate rifle.” — Jack A.
“My old (complete) A2 upper has been sitting forlorn on a shelf for a couple of years now. Perhaps I need to do a [Standard Modern Military] build of my own.” — Derek D.
Dennis Santiago replied: “Derek — that’s the reason I was attracted to this. I had bought a brand new WOA A2 pin upper receiver to make a new upper then the scope rule was adopted and it was all flat tops. This gives new purpose to the old parts.”
CMP Rules Defining Modern Military Rifles
Standard vs. Unlimited, Class A vs. Class B
There are actually two different classes of Standard Modern Military Rifles, Class A for AR-type rifles and Class B for other military-style rifles, such as the M1A and FN-FAL. Ok, got that? Now, in addition, there is also a second division for UNLIMITED Modern Military Rifles, again with two classes (Class A — AR-type and Class B — other military rifles). These unlimited rifles can have optics, heavier weights, modern-design adjustable-length stocks, and other upgrades. Here is Rule 5.2.2 from the current CMP Games Rifle and Pistol Competition Rules:
AR-platform rifles can be maintenance-intensive beasts. They need regular inspection, cleaning, and lubrication. But some AR owners make the situation worse by not regularly cleaning important small parts, or by using too MUCH oily/greasy lubricants in the wrong places. A properly maintained and lubricated AR15 can shoot hundreds of rounds (between cleanings) without a problem. If you learn where (and where not) to apply lubricant, you’ll find that your AR will run more reliably and the task of cleaning the bolt, bolt carrier, and upper receiver internals will be less of a burden.
Here we showcase videos that show how to field-strip an AR-15, inspect the key parts, clean components, and lubricate internal parts as needed. Along with these videos, we recommend you read the comprehensive AR-15 Gun Cleaning Clinic article on the Brownells website. This explains in detail important procedures that the videos might only cover in a few seconds.
If you want to keep your black rifle running smoothly and reliably, you must clean it regularly and follow the correct maintenance procedures. Here are five videos that explain how to properly disassemble and clean AR-platform rifles.
1. How To Clean Your AR-15 | Cleaning and Maintenance Tips
This is a quick 90-second starter video that may help new AR owners. Ricky Lehnhardt of OTIS Technology demonstrates the basics of cleaning and maintaining your AR-15. Lehnhardt does a good job identifying the points that need cleaning on the inside of ARs. However he works very quickly in the video. You may want to pause the video at some points. Also, Lehnhardt employs a cable for pulling patches and brushes through the barrel. Yes this is fast and easy. However, for match AR rifles, we recommend that you instead use a cleaning ROD with fitted bore guide.
2. Take-Down and Full Cleaning of AR-15 by Jerry Miculek
Here ace shooter Jerry Miculek takes down and cleans an AR-platform rifle belonging to his daughter Lena. This is a good video because Lena’s rifle was “run hard and packed up dirty” so you can see where carbon and grease build up. This 35-minute video is very thorough. Jerry is one of the nation’s top action carbine shooters, so listen carefully to his advice on cleaning and lubrication.
3. AR-15 Maintenance: Field-strip, Clean and Lubricate an AR-15
Gunsite Academy instructor and gunsmith Cory Trapp demonstrates the proper way to field-strip, clean, and lubricate an AR-15 carbine. In this 30-minute video, Trapp offers several important technical tips and hints. For example, at 11:05 Trap demonstrates how to determine if your bolt needs new gas rings. Along with cleaning procedures, this video explains how to inspect key components and how to function-test your AR before each shooting session.
4. AR-15 Dissassembly and Cleaning Guide
This video does a good job, with close-ups, showing how to remove the bolt carrier and clean the inside of the upper receiver. Then you can see how to work with various tools to clean the bolt, bolt carrier, and inside of chamber. We also recommend that you inspect the ejector recess and extractor recess. When we’ve inspected ARs that failed to cycle properly, we have often found nasty gunk (mixture of carbon, greasy lube, and brass particles) in these areas.
5. Basic AR-15 Quick and Easy Field Maintenance
In this NSSF-sponsored video, pro shooter Ryan Muller demonstrates basic, quick field maintenance of his AR-15. This would be for a quick cleaning and lubrication of the reciprocating parts. This covers rapid maintenance in the field. For full field-stripping and thorough cleaning, watch the previous videos.
Handy Mat for Cleaning AR Rifles
When working on an AR-15, it’s smart to have a pad that can absorb solvents and cushion your upper and lower. The $24.99 Real Avid Smart Mat is a good choice. This features printed take-down instructions and it has a handy parts tray on the right side. The mat rolls up for convenient storage. Click HERE to learn more.
Vital Inspections You Should Do After Disassembly
Last but not least, here are recommended inspections you should do every time you do a full field-strip and cleaning of your black rifle:
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Americans love AR-platform rifles. However, they can be maintenance-intensive, as hot gasses are directed right back into the action to operate the bolt. Because ARs have a somewhat unique (and dirty) semi-auto operating system, we think all AR owners should learn how their rifles operate — from the inside out. This feature provides an “inside look” at the AR, with X-Ray and Cutaway views created through advanced 3D computer modeling.
AR15 Functions Revealed with 3D Computer Animation
Ever wondered how the parts inside an AR15 work together? Just exactly how does the reciprocating bolt carrier feed rounds from the magazine? How do the elements in the trigger group work and reset after each shot? How does the gas system bleed gas from the barrel and operate the bolt carrier? These and other questions are answered in this eye-opening video from 45Snipers. Using “cutaway” 3D computer animation, this 5-minute video shows all features of an AR15 inside and out. This fascinating firearms animation allows the viewer to look inside the upper and lower receivers, into the bolt carrier, chamber, barrel, and magazine.
This video starts off slow and has annoying background music, but it is well worth watching if you own or shoot any AR-platform rifle. It illustrates all the key operations during the charging, loading, firing, and ejection processes. The cutaway animation shows how rounds are stripped from the magazine and then chambered. It then shows how every part of the trigger group works, and how the firing pin strikes the primer. You can even watch the bullet move down the barrel before the empty shell casing is removed from the chamber and tossed out the ejection port. Here are sample frames from the video:
How AR-Platform Rifles Work — General Introduction
To help reader understand the general operation of AR-type rifles, this video shows the control functions of an AR and how the upper and lower sections work together.
Cutaway 3D Animation of AR15/M16 Action — Watch Video
Here is an excellent “cutaway” animation by Thomas Schwenke that shows how an AR-15 functions — how the entire loading cycle works from start to finish.
AR platform rifles are semi-automatics version of the M16. These feature distinctive upper and lower receivers which can be readily separated via front and rear pins. The upper includes the barrel, handguard, forward gas tube, and bolt assembly, while the lower contains grip, trigger group, fire selector, and mag well. In addition the lower is attached to the stock which encloses the buffer assembly.
The original ArmaLite AR-15 was a select-fire, air-cooled, gas-operated, magazine-fed rifle designed by American gun manufacturer ArmaLite in 1956. It was based on Armalite’s AR-10 rifle chambered for the 7.62×51 NATO (.308 Win). In 1959, ArmaLite sold its rights to the AR-10 and AR-15 to Colt. Some key modifications were made — most notably, the charging handle was re-located from under the carrying handle to the rear of the receiver. The redesigned rifle was adopted by the U.S. military as the M16 carbine, which went into production in March 1964.
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Ever wondered how the parts inside an AR15 work together? Just exactly how does the reciprocating bolt carrier feed rounds from the magazine? How do the elements in the trigger group work and reset after each shot? How does the gas system bleed gas from the barrel and operate the bolt carrier? These and other questions are answered in this eye-opening video from 45Snipers. Using “cutaway” 3D computer animation, this 5-minute video shows all features of an AR15 inside and out. This fascinating firearms animation allows the viewer to look inside the upper and lower receivers, into the bolt carrier, chamber, barrel, and magazine.
This video starts off slow and has annoying background music, but it is well worth watching if you own or shoot any AR-platform rifle. It illustrates all the key operations during the charging, loading, firing, and ejection processes. The cutaway animation shows how rounds are stripped from the magazine and then chambered. It then shows how every part of the trigger group works, and how the firing pin strikes the primer. You can even watch the bullet move down the barrel before the empty shell casing is removed from the chamber and tossed out the ejection port. Here are sample frames from the video:
Video find by Grant Ubl. We welcome reader submissions.
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Do you need a quality, affordable lower for your next black gun build? Here’s one of the best deals we’d found. Palmetto State Armory (PSA) now has stripped AR15 lowers for just $59.99. With this lower as the core, you can build up your AR for any discipline you choose: 3-Gun rifle, competition service rifle, varmint rifle, or even “race gun” for the popular PRS Gas Gun Series (see below).
This video shows how to assemble a complete AR lower starting with a PSA receiver:
These forged PSA lowers are quality-made using 7075-T6 Aluminum. Finish is Black Hardcoat Anodized per MIL-8625 Type 3 class 2.
PRS Gas Gun Series — What You Need to Know
PRS Gas Gun Series Basics — How to Get Involved
Capitalizing on the success of the bolt-gun competitions, the PRS allows gas guns at many matches with a specific class for semi-auto rifles such as AR15s and AR10s. The inaugural 2017 PRS Gas Gun Series competition took place February 17-19, 2017 at the CORE Shooting Solutions range in Baker, Florida. Now there are PRS Gas Gun Matches around the country.
PRS Gas Gun Series Rules
For the new PRS “Gasser” Competition, the PRS developed rules on gun types, scoring, match timing, penalties, safety and other key topics. Gas gun division rifles may consist of a large or small frame semi-auto rifle with a maximum caliber of 7.62 mm (30 caliber) bore.
Open Division: The Open Division rifles will not exceed a caliber of .30 or a velocity of 3,200 fps. A match DQ will result any rounds over the speed limit of 3,200 fps (+/- 32 fps for environmental factors and equipment discrepancies). Match Officials may request at any point during a match that a competitor fire their rifle through chronograph. If the bullet exceeds the 3,200 fps speed limit, the shooter will receive an automatic match DQ.
Tactical Light Division: Intended to allow competitors the opportunity to compete using traditional military and law enforcement caliber. This promotes Active Duty military and law enforcement competitors use of their Service and Department-issued rifles. Tactical Light Division rifles are restricted to 5.56 NATO/.223 Remington calibers only. Bullet weight cannot exceed 77 grains and muzzle velocity cannot exceed 3,000 fps.
SSUSA: What will be the format of the PRS Gas Gun Series matches?
Wiseman: The matches will be a two-day format with 8 to 10 stages per day. There are three Divisions: Tactical Light for 5.56x45mm NATO/.223 Rem. rifles; Tactical Heavy for 7.62x51mm NATO/.308 Win.; and Open for everything else up to .30 cal. The maximum distance will be 800 yards.
SSUSA: What guns do you expect to be popular?
Wiseman: In the Open Division, I expect to see a lot of 6.5 Creedmoors for two main reasons; it’s an inherently accurate cartridge and Hornady makes great ammo for the folks that aren’t into reloading. I think the Tactical Light Division will probably be the most popular. It is hard to say specifically what rifles will be the most popular but there are a few AR companies that are known for the accuracy.
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5. Gas Block: You want a gas block that does not impose pointed stress on the barrel. Clamp-on types that grab all the way around the barrel are excellent. The blocks that are pinned on with tapered pins that wedge against the barrel or the slip on type of block with set screws that push up from underneath (or directly on the barrel) can deform the bore inside of the barrel and can wreck the accuracy of an otherwise great barrel.
