AR-15 Maintenance and Gunsmithing, Part 1
Tips for maintaining and building America's favorite rifle.
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AR-15/AR-10 Maintenance Notes
The rifles originally designed by Eugene Stoner have become a mainstay in many shooting realms. They have grown to become America’s rifle and have garnered a worldwide adoption. The proliferation of components, parts, kits, firearms, and ammunition are incredible, spurring on more demand.
With millions of rifles and pistols based on the AR, the consumer and real world user of the AR system should be well aware of the maintenance and armory needs of the platform - and when to replace parts or perform maintenance.
That’s the goal of this article: to speak to the importance of having parts on hand; lay out a relative spectrum of maintenance and parts checking and provide a good checklist regarding how and when to feed your machine, so it stays in optimum working order.
AR Parts Must-Haves
Spring Kits - as in more than one - or at least more than one of the essential springs
A Rise Armament trigger group can be useful
A full pin replacement set (including detent cups, etc.)
An extra gas tube for your selected system length
A carrier key and screws
Extractor and ejector (the ejector usually comes as part of the pin kit or full parts kit)
A buffer tube and spring
Sprinco magazine spring kits to ensure your mags won’t fail
Basic maintenance tooling like a Geissele barrel wrench and sight adjustment tools and carbon scraper, etc.
A hammer and punch set, including a roll pin punch set for those that don’t like seeing deformation on roll pins
A good set of rags and a solvent you trust along with a thin gun oil and a thicker gun grease; preferably a molybdenum disulfide or copper disulfide, or something that can be monitored more easily and trends “dry”
Some blue Loctite or similar thread locking compound - red if you’re daring (but don’t blame us if you cannot get parts apart again with the red)
How Regularly Should You Check for Wear and Tear?
Below we will detail a specific regiment and tweak it slightly for different types of volume shooters. You should always be on the lookout for things that don’t feel “right”, though. Be aware of your firearm and stop if you feel like something wasn’t normal.
Don’t be afraid to check why a round did not seat properly, or a load felt too weak or too strong; or you were several inches off target.
How Much Lubrication and What Types Make the Most Sense for an AR?
Guns in general need less lube than one might think. Most firearms only have a few places that require lubrication because of several reasons:
Unless a surface treatment is non-existent (meaning bare metal, oil or other lubrication is generally reserved for the areas where actual friction or consistent metal on metal contact occurs
Oil and other lubricants can actually increase the opportunity for debris collection and increase potential malfunctions in certain places on a firearm
Heat is an important factor to keep an eye on, but with regards to firearms, lubrication isn’t generally centered on places of high heat, like it might be in a different type of industrial application (e.g., in a motor, or as a coolant in a passive cooling system on an electrical system)
Oil can be messy and annoying during the firing of a firearm
Very few parts interact with each other in firearms on a metal-to-metal surface level, and if they do the spot of contact is tiny relative to the firearm, generally
Many firearms utilize different composites, hybrid systems or simply different materials in conjunction and with physical connections to other parts
Barrels, bolts, and trigger systems have specific hardness ranges that play well with each other to minimize wear potential. In the case of an AR, a hardened steel bolt rides in a hardened steel carrier, with a hardened steel cam forming a physical connection between them. They are hardened to within a few RC (Rockwell C-Scale hardness level of each other). The harder a steel part is, generally the less easy it is to mark up or degrade the surface through friction (even if extreme hardness can sometimes cause steel to become brittle upon impact). These parts are riding in anodized aluminum upper receivers and mate with a hardened chamber and a hardened and chrome-plated gas system, generally. The net requirement for lubrication on a liberal basis is about 8-12 drops of oil for most guns at any given time.
Aluminum And Steel Don’t Make Good Partners When You Introduce Certain Chemicals
Speaking of hardened steel riding in hard anodized aluminum - aluminum and steel don’t play well together under certain circumstances. Here are a couple of reasons why they don’t:
Even though the Aluminum is “hard anodized” it doesn’t mean that it’s anywhere near as hard as a piece of hardened steel on the upper end of the RC scale (most bolts and carriers are more than 62RC and some around 70-85RC - especially surface treated specialty object). The treatment is only a few millimeters thick. The upper receiver for example might be measured on an objectively different hardness scale, like the Brinell, Vickers or Rockwell B scale.
Hard anodizing is almost more art than it is science. Yes, of course certain levels of chemicals are needed, and yes, there is a best practice for how to perform the task, but no two batches are really the same
When aluminum (bare) and steel (bare) come in contact and sit in close proximity for extended periods of time - leeching and corrosion can occur. Finally the connection can cause real world issues in the form of heavy corrosion
Furthermore many lubricants and solvents can cause corrosion in dissimilar metals when they sit together in that solvent or lubricant.
Here’s what you need to know about to keep them operating safely and smoothly without premature wear:
A thin layer of grease is often better than no lube for wearing surfaces like the interior round-shaped channel of the upper receiver; it’s usually much better than oil, which can have more powerful solvents included in their chemical composition
Using molybdenum disulfide or a similar “dry grease” type (thing choke tube lube) can have a drastic impact on longevity - ensure they grease you use will not embed into the aluminum and is safe for use on dissimilar metals
Thin is your friend - don’t use streams of oil, wipe oil to fully coat the area and check for specific areas of wear which can be manifested by the consistent degradation of the surface area in a place where two dissimilar metals have been in repeated contact
What Needs to Be Cleaned Every Single Time You Shoot?
An important note: never fire a cartridge that the barrel is not marked to accept, or for which you are uncertain of the pressure standards relative to the barrel. E.g., do not fire a 5.56x45mm in a .223 marked barrel, unless it is also marked as capable of firing 5.56x45mm.
There are many schools of thought on this one. And really it depends on how much you shoot and how bad the ammunition fouls the key areas (bolt face/gas system/extractor/chamber/bore).
If you are not seeing much fouling and don’t see anything wrong during your safety checks after shooting and before your next outing, you can probably get by without a cleaning or with a basic wipe-down of these areas. No matter what, every 500 rounds you should be at least field-stripping and cleaning key areas to ensure that you can operate safely.
Depending on how tough you are on your guns and the environment (think flying sand, etc.) and the type of ammunition/cleanliness of the ammunition - this could be every 100 rounds, or every 250 rounds fired.
Generally, most commercial factory fresh loads will afford you decent cleanliness and your gun won’t be having difficulties for 500 rounds, where it needs to be cleaned before you finish that range session.
There is no reason you cannot make a check every magazine load or a significant check if there is a misfire, misfeed or malfunction.
Every 100 rounds you should be checking for basic cleanliness to keep your gun running smoothly. There are times/conditions where you can get away with firing 1000 rounds without a thorough cleaning, but it’s highly recommended you don’t do that.
Any time you see or feel the following, you should stop what you are doing and check the gun thoroughly for safety concerns:
A round that didn’t feel right; recoiled incorrectly (too hard OR too soft); or any round that seemed too loud compared to others, or too quiet
Any malfunction that cannot immediately and definitively be attributed to a bad primer or a case with a nick in it, etc.
Multiple extraction failures in a single magazine
Striated or cut cases that seem inappropriately abused
Any case head separation
Any malfunction not easily resolved by a forward assist or by re-racking the charging handle
You should clear the firearm and ensure it is unloaded before attempting any other safety check.