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Insight into owning and building a BushMaster AR-15 based on a paper written by Mr. Ron Wu


Mr. Ron Wu has kindly granted us permission to reproduce his paper on owning and building an AR-15. It answers many of the questions that come in to our Customer Service and Technical Support lines every day. We thank him for his cooperation and recommend this as preliminary reading for the prospective owner/builder. Disclaimer: The purpose of this Primer is as a guide and introduction to AR-15 rifle collecting and building. The author - or Bushmaster Firearms, Inc. / Quality Parts Co. - assumes no liability for accuracy of the information herein contained. Additionally, the author and Bushmaster Firearms. Inc. urges the reader and prospective AR-15 builder to check state and local regulations regarding the AR-15 type rifle. This article was written in 1997 and does not take into account the effects of the newly passed SB-23 Legislation for California AR-15 owners.


For prospective builders, bear in mind also that pricing has changed - in some cases dramatically - for rifles, assemblies and parts since 1997(Bushmaster's note: Current pricing for all Bushmaster products can be found in the catalog pages of this Website.) Firearm Regulations Information: Please contact the BATF for any and all questions regarding Federal firearms regulations at 414-679-5040. For California firearm regulation information, contact the California Department of Justice at 800-952-5225.

Note on Pre- vs. Post-Ban Rifles:




The AR-15 Rifle: Was designed by Eugene Stoner and his team of engineers in the 1960’s for entry into U.S. military trials for a new battle rifle to replace the M-14. Mr. Stoner, working at the time for ArmaLite (a division of the Fairchild Aircraft & Engine Corporation), engineered a revolutionary new rifle utilizing non-traditional rifle materials such as aluminum alloys and plastics. It was initially designed around the .222 Remington cartridge. It was later, at the request of the Army, re-chambered in .223 Remington (5.56x45mm) which propelled a 55-grain bullet out of the AR-15 at roughly 3000 ft.-plus per second. With the .223-calibered AR-15 rifle, for the same weight, a soldier could carry more ammunition than the older .308 Win. (7.62x51mm) ammunition for the heavier M14 rifle. After lengthy evaluation and revisions, the U.S. Air Force for use adopted the AR-15 rifle by its base security personnel.

For a variety of political reasons, the Army did not select the rifle. However, as America became involved in the Vietnam War, Secretary of Defense James McNamara cut through the Army Ordnance Department’s red tape and selected the AR-15 for issuance to troops. The Army gave it the military designation of "M16".In the Vietnam War, the rifle initially earned a reputation as being prone to jamming and stoppages. This was, in hindsight, due to three primary factors: 1)insufficient training of the troops on rifles maintenance, 2) poor-to-non-existent distribution of cleaning kits to those same troops in the field, and 3) improperly formulated .223 Remington ammunition which caused heavy fouling (a primary cause of stoppages). Eventually, the situation was recognized and remedied as troops were properly trained to keep their rifles clean and well-lubricated, issued proper cleaning kits, and issued .223 Remington ammunition that was properly formulated to burn cleanly.

The AR-15 Legacy

Today, the AR-15 rifle has become really one the most highly engineered and refined battle rifles of modern armies. It has since earned a reputation for reliability and accuracy. It has been in service in all branches of U.S. Armed Forces now for nearly 30 years. In the process, it has been upgraded from the "M16", to the "M16-A1", all the way through the latest "M16-A4". The U.S. Marine Corps (USMC) and the U.S. Military Special Operations Command (SOCOM) also currently issues to its troops, the M-4 rifle, which is essentially an M-16 with a 14.5" barrel, collapsible stock, detachable carrying handle, and other special accessories such as laser/infrared sighting systems, reflex-type optics, grenade launchers, flashlight attachments, etc. For these Special Forces, the M-4 has also been in certain instances reconfigured to fire "full auto", as opposed to "tri-burst". 

The current generation of military M-16’s and civilian AR-15 models differ from the originals in many ways, reflecting the improvements and refinements of the rifle over the last 30 years. Current Military Specifications (Mil-Spec) for the rifle’s barrel is for a heavy barrel (HBAR), replacing the original lightweight barrel which was prone to overheating and bending. Nearly all-current civilian AR-15’s now are built with Mil-Spec HBAR’s. The original triangular-shaped, non-perforated handguards have been replaced by rounded, perforated, and heat-shielded handguards for rapid heat dissipation of the barrel. Other changes include; a tri-burst sear on the M-16 replacing the fully automatic sear of the original, adding a brass deflector to keep spent cartridges out of left-handed shooters faces, adjustable front sight and fully adjustable rear sight for windage and elevation, detachable carrying handles, etc.

Today’s military contract for the M-16 variants has been awarded to FabriqueNationaled’Armes de Guerres (FN) of Belgium (though the actual rifles are built here in the United States). Colt’s Manufacturing’s Co., who lost the lucrative M-16 contract, has retained the smaller contract for the M-4 rifle mentioned above. It has been reported that prior to Colt’s obtaining the M-4 contract, Bushmaster Firearms Co. had manufactured a limited run of M-4’s. (Note: According to recent firearm industry news, as of December 1997, Colt was attempting to acquire FN, but the deal fell through under opposition from the Belgian government.)

What's in a Name?

The name, "AR-15", is in general, used by the shooting public in reference to current rifles (regardless of manufacturer) made to look, function, and swap-parts with the AR-15. Non-military contract AR-15’s are also commonly referred to as "clones". The actual and original "AR-15", manufactured by ArmaLite and then Colt (after Colt bought the manufacturing rights from ArmaLite) has been discontinued for political reasons. Each manufacturer of AR-15-patterned rifles now has its own moniker for the rifle these days; like Colt’s "Match Target", Bushmaster’s "XM15E2", DPMS’s "Panther", and the hilarious Olympic Arms’ "PCR"—for "Politically Correct Rifle".

Civilian Ownership


As a result of the military’s adoption and continued usage of the rifle, the shooting public is blessed with a variety of manufacturers of AR-15 variants. The major manufacturers today are: Colt, Bushmaster, Defense Procurement Management Services (DPMS), Olympic Arms, and ArmaLite (Note: The rights to the name "ArmaLite"—which was out of the small arms business years ago—have been bought and sold to Eagle Arms). Parts, whether newly manufactured or surplus, are plentiful from dozens of companies - which will sell you non-restricted parts. Pick up a copy of Shotgun News at your local newsstand and you will be sure to see a variety of advertisements for AR-15 parts suppliers. (Bushmaster note: See our advertisements in every issue of Shotgun News.)

Legal Configurations for Civilians

  1. BATF: The Bureau of Alcohol, Tobacco, and Firearms is the Federal Agency responsible for the enforcement of Federal firearm regulations. The BATF takes very seriously any and all infractions of these laws. Ignorance here, shooters, is definitely an offense not a defense! So, stay on the safe side and follow all Federal, State, and Local firearm rules and regulations.
  2. Pre-Ban vs. Post-Ban: Today, if you are interested building your own AR-15 rifle then you are limited to building Post-Ban configurations of the rifle. This may or may not disappoint you. But you ask, "What is Post-Ban ?" Well, the short of it is, The Crime Bill, courtesy of the Clinton Administration, has made a number of features illegal on civilian-owned semi-automatic "assault rifles" (i.e. AR-15, AK-47, FN-FALL1A1, etc.) manufactured after September 1994. In general, "assault rifles" manufactured after September 1994 are referred to as "Post-Ban", and conversely those manufactured prior to September 1994 are referred to as "Pre-Ban."Notes on Pre- vs. Post-Ban Rifles: In certain limited circumstances, you may still build or own a Pre-Ban AR-15 rifle. But the restrictions should be researched extremely carefully and followed to the letter of the law! Should you desire to build or own a Pre-Ban rifle, then please be sure to read Section 4. "But I Want a Pre-Ban Rifle". Californians should be especially mindful of impending legislation - California State Bill SB-23. IT IS VERY IMPORTANT TO NOTE THAT A LOWER RECEIVER WITH SERIAL NUMBER WHICH DENOTES MANUFACTURING PRIOR TO SEPTEMBER 1994 DOES NOT NECESSARILY PERMIT YOU TO LEGALLY BUILD A RIFLE WITH PRE-BAN FEATURES!A LOWER RECEIVER MUST HAVE BEEN ASSEMBLED INTO A COMPLETE RIFLE PRIOR TO THE SEPTEMBER 1994 BAN AND THE MANUFACTURER MUST BE ABLE TO DOCUMENT THAT ASSEMBLY TO THE BATF IN ORDER TO QUALIFY AS A PRE-BAN LOWER RECEIVER!
  3. Ban Criteria Features: Post-Ban AR-15 rifles, by law, cannot have more than 2 of the following features:
    1. Detachable magazine
    2. Pistol grip
    3. Threaded barrel/flash hider
    4. Collapsible stock
    5. Bayonet lug
    6. Grenade launcher
  4. What Features to Keep: Ninety-nine percent of Post-Ban-AR-15 rifle owners keep the detachable magazine and pistol grip features. - And for good reason. In many ways the [Crime Bill] Ban (though an infringement on our 2nd Amendment Rights), by limiting the accessories on the AR-15, has actually improved the performance of the rifle. It is more accurate with a crowned barrel vs. a threaded barrel for flash hider. It is more comfortable for most shooters with the regular stock vs. the shorter and smaller collapsible stock. It weighs much less without a bayonet and grenade launcher. As well-built and engineered as it is, the AR-15 with bayonet does not make a great platform for a spear - application of said spear would probably ruin the alignment of your front sight and barrel. And, the M203 grenade launcher is a costly and difficult-to-find civilian "flare launcher".

Barrel Options

  1. Barrel Length: The military issues chrome-lined 20" heavy barrels on all their M16-series, and also 14.5" heavy barrels on the M4. Barrels, however, are manufactured in everything from pistol-length 7-1/2" versions to match-grade 26", and everything in between. (Note: Federal, State, and Local laws all dictate that minimum rifle barrel length is 16". Do not build any rifle with less than a 16" barrel.) Civilians have mainly a choice of 20", 16", and 24". 20" is standard. 16" is carbine length. 24"-26" is usually reserved for match-shooters and varmint hunters. Barrels are machined from a variety of steels or stainless steels. (Bushmaster note: Bushmaster uses mil. spec. Chrome Moly Vanadium steel and chrome lines the bore and chamber on all but its DCM Competition barrels.)
  2. HBAR: Steel or Chrome-lined?: Also, as previously mentioned, HBAR’s are the current mil-spec. They offer greater accuracy and are less prone to overheating. It is essentially the only barrel type that many manufacturers make these days. But, you have the option of plain steel barrel or chrome-lined barrel. Some shooters feel that a plain steel barrel is more accurate than a chrome-lined barrel, which is why most match-shooters use steel. Chrome lining is much more durable than steel. Note: Break-in procedures for the 2 types vary greatly! Check with your manufacturer or someone knowledgeable before shooting your new barrel for the first time to avoid ruining it!) Bushmaster note: To satisfy the Competition shooters, Bushmaster's DCM rifle features a plain steel barrel in 1 x 8" twist for stabilization of the heavier competition bullets.) In my opinion steel is fine and chrome-lined is...also fine. Under full-auto, military-type conditions I can definitely see the need for the durable chrome lining. However, civilian shooters—even the occasional happy blaster—is not going to wear out a steel barrel for many thousands upon thousands of rounds in recreational (non-full auto) shooting, given proper care of the barrel. But know that chrome-lined barrels are much easier to clean and resistant to rusting. So if you’re not one for rifles maintenance, it may behoove you to order the chrome-lining. 

Parts Ordering

Companies that supply AR-15 parts can legally sell to anyone Pre-Ban parts, Post-Ban parts, and less-than-16" barrel parts. The exception is the serial numbered lower receiver, which can only be sold through FFL dealers. It is up to you to follow the laws that pertain to your jurisdiction. These parts companies are not legally required, as far as I know, to screen their customers. So, be very careful to order Post-Ban parts! (Note: You can still obtain legal Pre-Ban AR-15 rifles and, as mentioned before, Pre-Ban components, though they are much more expensive and getting more difficult to find. See "But I Want a Pre-Ban Rifle" section below.)

Automatic/Select Fire Versions

Automatic firearms have been tightly regulated in the United States since the Gun Control Act of 1934. Automatic and Select-Fire Versions of any firearm are considered Class III firearms and subject to National Firearms Act (NFA) Title II regulations, which are extremely strict. Newly manufactured fully automatic and select-fire versions are available only to the military and law enforcement, and in extremely limited circumstances to civilians. In California, you can forget owning an automatic anything unless you are law enforcement officer, or a licensed dealer.Civilians must obtain special law-enforcement approved permits, pass a whole series of Local and Federal background checks, and pay a host of special Federal Transfer taxes ($200.00 per firearm) to own an automatic or select-fire firearm in the few states that permit them for civilians!Remember, it is ILLEGAL to even have in your possession the parts for Automatic/Select Fire conversion for your AR-15 type rifle if you have a semi-automatic AR-15 rifle! Be safe, err on the side of caution, and stick to the legal semi-automatic parts. If you have any questions as to the legality of any parts you may have, call Bushmaster Sales at 1-800-998-SWAT or Customer Service at 1-800-883-6229.

How to go About Building Your Own AR-15 & Why

The Savings

Most people build their own AR-15’s in order to save money. Some build their own for the knowledge and experience. A combination of both is the best reason in my opinion. In California, a newly manufactured, basic AR-15 model from any manufacturer, will have a retail sticker price in excess $900.00 (base price). Then do not forget to include California Sales Tax (8.25%) and DROS Fee (California Dept. of Justice’s $14 processing fee). This brings your total to $988.25, quite a chunk of change. Now, let’s compare this to building your own rifle. Without getting into the intricate details yet, it suffices to say that the Federally-regulated, "serialized" (numbered) component, called the lower receiver, will cost you about $150.00 from your local FFL gun dealer (maybe less if he is kind). Your local FFL gun dealer is the only source for this part, as only the lower receiver is considered the actual firearm under the law. The rest of the AR-15, in the form of a "kit", will cost about $380.00 delivered to your door—with no middleman. That brings your total cost to just $530.00. Even adding in the carrying strap and 1 magazine—usually included on retail versions—your cost is only $550.00. That’s $438.25savings—or 44%! The saving is equivalent to roughly 2000 rounds of .223 Remington ammunition! Morals to the story build your own! (Bushmaster's Note: Remember, pricing has changed considerably since this was written in 1997.)

What to Order

The ordering process will require that you order the parts from 2 different companies in order to save the most money. The "stripped" lower receiver—devoid of all other parts—will have to be ordered through your local FFL dealer. I suggest using Bushmaster lower receivers—who have a good reputation in the business, and Bushmaster manufactures their parts with top-quality materials.

  1. Step 1: Purchase or Order a Lower Receiver through your local gun dealer/FFL holder or Dept. Armorer if you are in Law Enforcement.
  2. Step 2: Order "The Kit" (less Lower Receiver). You will receive a complete "kit" with all parts except the lower receiver. The barrel will come pre-assembled—saving you the time, effort, and critical part of test firing! (Bushmaster's Note: Our kits range from the 16" Bbl."" Carbine at $585.00 up to the 26" Bbl. Match Target Model at $605.00. You'll have to make various "options" decisions at this point. Some Bushmaster options include: A1, A2 or Flat-top Upper Receiver style; Barrel Fluting ($50 extra); Full or "milled" front sight base; factory installed muzzle brakes. Call the Bushmaster Sales team - 1-800-998-SWAT - for help with any questions regarding these options.)

Necessary Tools

Although opinions vary as to the number of "proper tools" you need. In my experience, only the following was necessary:

  1. Long screwdriver
  2. Set of drift punches (Bushmaster's Note: our 4 piece drift punch set - is $14.95 - part # STAPNCHSET )
  3. 16 oz. brass hammer (a regular hammer will do in a pinch, but use lightly!)
  4. Set of maintenance materials: gun cleaner (i.e. Hoppes No. 9), gun oil, patches (Bushmaster's Note: see our Gunsmithing Tools & Supplies Section)
  5. A pair of needlenose pliers
  6. USMC Technical Manual (TM 9-1005-319-23&P). A must-have reference guide on assembly, disassembly, and cleaning (Bushmaster's Note: Manuals for either A1 or A2 available at $10.95)
  7. (Optional) AR-15 Assembly/Disassembly Video. $19.95. Available from Bushmaster (Bushmaster's Note: Video part # is ADS-001)

Accessories and Options

As previously discussed, there are options and extras, which you should know, are available to you for more money - of course. Some you need some you don’t. These are matters of personal preference, and I don’t know the charges for many of them:

  1. Heatshields. These are about $5.00 extra, and are worth it! They keep your front handguards cooler in extended shooting sessions (Bushmaster's Note: heatshields are included with handguards in our Kits or Upper Assemblies.)
  2. Flat-Top Upper Receiver: This option gives you a detachable carrying handle. This way you can take the carrying handle off and mount very low to the bore-line any type of scope on your rifle—full sized, compact, reflex, etc. Very cool in either 20" or 16" versions with red-dot or reflex/holographic type sights. Note: you can also mount scopes to the carrying handle, so a flat-top is not a necessity for scoping purposes. (Bushmaster's Note: The flat-top, or "V Match" Upper is a straight substitution option from Bushmaster. The A3 type Removable Carry Handle is an $89.95 optional item)
  3. Carrying Sling: $5.00 to $40.00. Self-explanatory, available in cheap but functional nylon form or high-quality leather. Buy at least the inexpensive nylon one, you will need it (Bushmaster's Note: we offer a variety of slings from $4.95 to $19.95)
  4. Repair Kit & Extra Detent Pins: About $30.00. Get one. Any AR-15 owner needs to have these parts on hand. Not those parts break too often, but normal wear and tear will occur. You should have 2 or 3 extra detent pins ($0.50/piece), because in the assembly process you may lose one or two for reasons that are too long to explain here—and if you don’t have a spare on hand then the whole assembly will be stalled until a $0.50 piece arrives by mail-order. (Bushmaster's Note: Our Field Repair Kit is $24.95; Pivot or Takedown Pins are $3.95 ea. and their Detents are $0.50 ea.)
  5. Free-Floated Barrel: About $25.00 extra. Free-floating the barrel does exactly that. It "floats" the handguards off the barrel, making your rifle like a hunting rifle where no "pressure" from the handguard canbe transferred to your barrel. Most people report that "free-floating the barrel" decreases their group size at 100 yards from something like 1.25" to .75". Note that should you opt for the free-floated barrel, the aluminum free-float tube is going to get hot in extended shooting sessions. (Bushmaster's Note: V Match "free floating" handguards can be ordered as an option on factory barrel/upper assemblies for $40.00 additional. To add them to an already assembled barrel require removal of the front sight base - we recommend that you have this procedure done by an experienced gunsmith. Bushmaster can do this for a small charge.)
  6. Fluting: Usually about $50.00 extra. "Fluting" is a process whereby multiple parallel grooves are actually cut into the barrel for its entire length. This process makes the barrel cool faster, makes it stiffer, lighter, and makes it more accurate. (Bushmaster's Note: Any Bushmaster barrel can be ordered fluted for $50.00 additional)
  7. Magazines: $10-30 each. Well, there are an endless variety of magazine manufacturers out there. And though the Brady Bill has limited newly manufactured magazines to 10-rounds capacity, there is plenty of 20-, 30-, and 40- round magazines in circulation (new and used) manufactured prior to the Brady Bill. The 30-rd Israeli-made; polymer "Orlite" magazines are about $15-20 and work great. The same can be said for the polymer Canadian "Thermold" magazines. (Note: It has come to my attention that the polymer magazines, i.e. "Orlite" and "Thermold" do not always positively lock into place in Bushmaster lower receivers. So, it is my recommendation to buy your magazines directly from Bushmaster, or buy G.I. surplus magazines, or Colt’s magazines.) (Bushmaster's Note: 20-, 30-, and 40- round magazines have now become scarcer. The Orlite magazines were originally designed for the Israeli Galil rifle and lack a notch that the standard AR type magazine has - which leads to occasional functional difficulties.)


The entire assembly process, presuming you have ordered the pre-assembled barrel parts, will take you no longer than an afternoon - 2 hours if you are good with mechanical parts and at following schematic diagrams. Again, here the USMC Technical Manual is essential, providing invaluable diagrams and schematics. There is also a good schematic you can download from the Bushmaster/Quality Parts Website ( Alternatively, you have the luxury of a first-rate Bushmaster video, though the extra $20 bucks isn’t really necessary. Read the USMC Technical Manual through once, then twice. After which, you will understand and have an overview of the entire project.

Really, it comes down to fitting some parts together and using roll pins to put the rifle together. If you have ordered the parts as described above, then your Upper Receiver and Barrel Assembly comes pre-assembled, and has generally been test-fired at the factory. It is a good idea to confirm this when you order from your parts supplier that, in fact, your Upper Receiver and Barrel Assembly has been tested for headspacing and test-fired. This dispenses with your need to test the headspacing of the chamber—though it is a good idea to have, and occasionally use, a "FIELD HEADSPACE GAUGE". It will come with instructions on how to periodically test your headspace to assure the safety of firing your AR-15 rifle. (Bushmaster's note: Headspace gauges: Go; No-Go or Field is $15.00 each.) I read a suggestion somewhere that you should put down and spread out a few large, spare white sheets in your living room or garage to keep from losing parts upon assembly. I have personally used this method,and have found it to be a great idea. Also, have a few paper plates ready to put all your little springs and detent pins into until they are ready to be used.

Clean all your parts first with BreakfreeCLP or like product - and if you have time, let the parts soak overnight. Also, please remember to wear safety glasses when you are assembling your rifle. All the little pins and springs become mini-projectiles that are a ballistic liability to your eyes! Trust me, I’ve had one or two close calls, being too cool to wear safety glasses in the presence of no one in my own garage. I now wear them whenever I work with the pins and springs! There is one tricky part in the assembly process. This is the front takedown pin’s detent spring and detent pin installation. This requires some patience and a few attempts. Brownells sells a special tool for this project. It is worth it the $7.95 if you are intending ever to construct 2 or more rifles. Otherwise, use a blade of some type, and be extremely careful of losing the spring and detent pin when installing them! (Note: One major discrepancy in the USMC Technical Manual’s instructions with regard to your semi-automatic version is the section on installing the firing control group and safety selector assembly. Simply forget about the USMC Technical Manual’s instructions regarding "automatic sear parts" installation, and the rifle will still come together fine. You may notice that your "safety selector switch" remains loose and free moving after installation of the firing control group and safety selector assembly. Don’t worry, upon installation of your pistol grip, the safety selector switch will tighten up and function reliably.) After assembly, you are ready to shoot your new rifle. Remember to properly break-in your rifle’s new barrel.

But I Want a Pre-Ban Rifle



This is an extremely important detail! This is why I highly suggest that when dealing with any "Pre-Ban" lower receivers, check the serial number with the manufacturer to confirm that it is indeed of "Pre-Ban" manufacture.Getting this confirmation in writing (i.e. by facsimile) is also not a bad idea!

So, you want all the goodies on your rifle? Well, you can still have them but it will cost you. Assembled Pre-Ban rifles sell for about 40-50% more than Post-Ban ones. So a rifle that costs about $1,000.00 retail, will set you back—if you can find one—closer to $1,400.00. That’s not a lot of money to some people who "have to have it all". With a Pre-Ban Rifle, you will then have the legal capacity to have: detachable magazine, pistol grip, threaded barrel and flash hider, collapsible stock, bayonet lug (bayonet sold separately), and grenade launcher (sold separately). (Bushmaster note: Remember, these are 1997 prices estimates.)

But, be careful! Some unscrupulous individuals will mate Pre-Ban parts and features onto a Post-Ban lower receiver and sell them as "Pre-Ban". This can get you, as well as the seller, into a load of trouble with all levels of Law Enforcement. It’s not worth the legal fees! Buy only from a reputable source. You can call any AR-15 manufacturer with the serial number of your lower receiver and they will tell you when the rifle was made and if it is Pre-Ban or Post-Ban. Can I build a Pre-Ban rifle to save money you ask? Why, yes. But it is difficult. Pre-Ban lower receivers are extremely difficult to find these days and are expensive, usually fetching in excess of $300.00 for the lower receiver alone. But should you be able to find one for sale; first, check the serial number with the manufacturer and if it is confirmed as a "Pre-Ban", then negotiate the sale. You will then build, as instructed above, but have the option of installing the "banned" features.


First, as always, with your rifle pointed in a safe direction, remove any magazine attached to the rifle, and confirm that the rifle is unloaded! Then, disassemble into its major components. The extent to which you disassemble is up to you. In general, I separate the upper and lower assembles, and then I disassemble the charging handle and bolt carrier group (I actually disassemble the bolt carrier group as described in the USMC Technical Manual). That’s it as far as disassembly. There’s a reason this is a military rifle. Maintenance must be easily accomplished in the field. (Note: I do not regularly disassemble the trigger group. This is not necessary most of the time. Should the area where the trigger grouping is installed become fouled to the point of affecting function or even your esthetic liking, then disassembling and cleaning the parts. Otherwise, there’s no reason to.) I, personally, spray down all the parts with MP-7 and let soak for about 15 minutes. Then using a cleaning rod chamber guide (this tool is essential to keep you from scraping up the insides of your
upper receiver chamber area with the cleaning rod—it also keeps the solvent confined to the bore), I scrub out the bore once, run a dry patch through, soak with MP-7 again for a minute or two, scrub, and run a dry patch through. And I’m done. (Note: if I’m not going to fire my rifle for a while, then I run a patch lightly coated with oil through the bore. I am always careful to run a dry patch through it before firing it again! Do not fire a rifle with an "oiled" bore! This can be extremely dangerous and cause hydraulic failures in your rifle—which in turn may cause "hydraulic failures" in you (i.e. bodily harm)!)

I’m sure to carefully and meticulously clean out the chamber area with solvent-soaked rags and use my Q-tips to a great extent here. Be careful to get out the entire "gunk" that collects between the locking lugs. This may take some scraping. Then, I clean out the rest of the insides of the upper and lower receivers. The bolt carrier grouping is rather simple to clean out with the exception of the inside of the bolt carrier itself. Carbon residue just seems to collect at the bottom of what
I’ll call "the well"—you’ll know what I mean when you see it—and no amount of solvent-soaking, scraping with Q-tips/dental picks, etc. seems to get it out. I finally resorted to buying Brownells AR-15 Bolt Carrier Scraping Tool, and voila, a 20-minute chore was turned into a 2-minute chore! (Bushmaster note: Our Gunsmithing Tools section shows two different Bolt Carrier Carbon Scrapers.)

After cleaning everything, I apply a light coat of Breakfree CLP to everything while being careful not to get any in the chamber or bore area. On surfaces subjected to great friction, i.e. the outside of bolt carrier, I put on a light coat of Snake Oil. Be careful not to get any oil on the face of the bolt itself!

I wipe down my magazines with a solvent-soaked rag, and occasionally disassemble them for a detail cleaning. You can also get these instructions for disassembly of the magazine from the technical manual.

After all this, reassemble, and perform a quick function check. With everything in order, my rifle is ready for storage.


Bushmaster again thanks Mr. Ron Wu for allowing us to publish his AR-15 Primer. If you have questions regarding his paper, he can be contacted at:

The addition of the "Bushmaster Notes" throughout Mr. Wu's "Primer" are intended as a convenient reference for the reader and are not part of Mr. Wu's original work as found on

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