AR-15 Maintenance and Gunsmithing, Part 2

Tips for maintaining and building America's favorite rifle.

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Properly Breaking in A Barrel

A barrel used in a basic AR won’t generally have a need for a specific break-in strategy, but it can be a best practice to observe the common principles of breaking in a barrel to ensure that no fouling is going to cause issues. Every competition shooter is going to have a regimen for breaking in a tight barrel to ensure proper accuracy. It’s hard to state one here that most will agree with.

Go easy on the lapping compound if you are breaking in a barrel for precision shooting and start with the highest grit (least aggressive compound).

To break in a barrel, take a shot then clean the barrel with a patch and oil. Avoid solvent during the initial break in phase unless you are prepared to fully clean the barrel to neutralize any etching potential from the solvent. 

After the next two shots do the same. Then take 3, clean with a patch and light oil. Each set of shots you will want to check the bore for fouling, flaking, debris and odd striations in the barrel caused by fouling.

This author prefers to use all copper rounds for the initial break in period because the monolithic build and the harder metallic compound tends to perform the necessary “smoothing” more easily with easier to see “fouling”.

You can repeat a couple more times until you have shot enough to feel comfortable with the basic rifling profile. Clean the bore and chamber thoroughly and then transition into the rounds you would normally plan on shooting. 

This is an incredibly basic barrel break in procedure - and if you are super concerned with your barrel, you should do your own research and get multiple viewpoints. Generally, the manufacturing attention to detail and the modular, general-precision nature of the majority of the AR’s on the market, barrel break-in is not a super-hyped component of preventative maintenance outside of ultra long range precision or competition shooting.

Only you will know if your AR may be steering towards more precision tasks and whether you need to explore the concept further.

What Are the Biggest Culprits for Compromised Reliability?

In no particular order:

• Poor quality ammunition

• Gas tube bending

• Weak mag springs

• Poor maintenance on the bolt/breech/chamber

• Modified buffer springs or cyclic rates by tension or weight

• Poor handling of the firearm 

• Too much lube

The Basic Maintenance Cycles for Shooters of the AR

Every 250 rounds - Perform a visual check; and a wipe down of key components *(bolt face and lugs; extractor area; chamber and feed area; bore; exposed gas system areas)

Every 500 rounds - another visual check and wipe down of key components since it’s a stop along the “every 250 rounds” arc; look at the magazines for excessive debris on followers or inside the first couple of inches of the magazine; basic visual check of the muzzle for accumulated debris; and the buffer tube area as well to ensure the debris is not excessive.

Generally, a close inspection of the hammer/trigger/sear from a visual level is helpful (a flashlight is a good tool here), and pay close attention to the carbon, debris and fouling on the bolt face, carrier gas area and the chamber.

Possibly running some solvent and cleaning the bore and chamber in addition to the wipe down of the key components will make sense. You will want to properly lubricate the appropriate areas of the firearm at this point as well. Note that additional lubrication will speed up the need for cleaning; especially if there is already accumulated debris and unburnt powder, etc. 

Additionally, at 500 rounds, you will have a good idea of how the rifle and the ammunition, and the magazines are prone to foul and how they behave relative to each other. 

Every 1000 rounds - a full clean with at least field stripping and close attention paid to the gas system components. 

Every 2500 rounds - checking for more excessive wear and tear in metal parts. Checking for excessive lead or copper fouling in any of the chamber or bore areas, including the muzzle brake area. If you are using a suppressor, you should be doing this at least every 1000 rounds, and more like every 500 rounds.

The additional debris accumulation can be a serious concern if you are not monitoring it. It can cause excessive pressure and lead to a special class of issues. Check how tight the handguard and internal fitment of parts is progressing.

Ensure that all component parts are still tightly locked down with mechanical fasteners. Check for excessive play in the pins and for weak springs. 

Every 5000 rounds - check barrel for excessive wear and check headspacing and basic measurements for your chosen ammunition/load. A full disassembly should be performed to ensure gas components are functioning properly and to check for excessive wear of components and for spring wear. Check for excessive pin looseness.

Check for any striations or detrimental effects inside of the chamber. Check the cam to bolt to carrier fitment and the front and rear of the firing pin. Check for deformation on the firing pin hole and any wear that looks uneven on the bolt face; lugs and chamber.

Check for any type of “peening” or “stretching” on any of the key components. Thoroughly clean with brushes and solvents to ensure that all excessive fouling is removed. Disassemble beyond the normal field stripping if possible. 

This is a good interval (5k rounds) to check for hairline cracks across all parts of the firearm to see if you can determine any impact deterioration or hard use concerns in the whole of the firearm.

Every 10,000 rounds, expect to do a spring update on buffers and magazines, depending on how many magazines you run. If you only run a couple, this is a good time to change them, as 5k+ rounds will be enough to possibly impact feeding reliability.

Your mileage may vary depending on mag type, manufacturer, and general usage statistics. Check trigger/hammer/sear surfaces for wear and degradation. **If at any time you have a multi-shot release (2-3-4 shot burst that is unintentional), you should immediately check these surfaces and the springs associated with the trigger group. 

Barrels for most normal velocity rounds (less than 3500 fps velocity on average) should last a range of 12-20K rounds or so.

If they are chrome lined you might squeeze a bit more life out of them, but that’s not as normal an option as it once was because the accuracy concerns and the fact that chrome lining didn’t mitigate normal wear most often for most shooters anyway. Additionally, there is less of a proliferation of “mil-spec” barrels like there once was. 

If you are shooting a very high velocity round or have a specialty upper that sees heavy velocity up-ticks for your chosen cartridge, or you are trying for the ultimate in accuracy you should begin monitoring the barrel for noticeable degradation in accuracy around 5-9k rounds and keep monitoring after that. Most barrels will be good past 12k rounds easily. 

If you are shooting multiple types of ammunition; particularly dirty ammunition; reloads that utilize lower quality powders or are in an environment that is particularly windy or dirty, you should increase the amount of checks/lower the time between intervals.

If at any time, you see a bulge or ring in the barrel, or any bore or chamber anomaly or deterioration, your firearm is not generally safe to fire. It should be checked by a qualified gunsmith, armorer, or replaced. 

Light Shooters

You’re most likely a light volume shooter if the following is a good representation of you and your habits when shooting an AR:

• Shoot less than once a month

• Shoot less than 100 rounds at each range outing

• Buying moderate or top quality ammunition with brass casings and decent powder and boxer primers

Here’s a good schedule for light volume shooters for maintenance:

You should clean the following areas of your gun at the paired interval: 

See the above content for the 250-round cleaning regimen. 

Generally, a light clean and wipe down and a basic bore cleaning with light oil or light solvent and then dried with patches and oiled lightly, will suffice if the interval and volume is so low. There are AR’s in existence that have never been deep-cleaned because the volume is so low.

You’d be surprised with the right ammunition and a basic wipe down, how much maintenance you can avoid if you shoot infrequently. 

You should expect to have the following parts and be checking for obvious signs of breakage, loss in fitment, spring tension and general wear at the paired interval and the listed locations on your firearm:

See the above content for the 2500 and 5000 round count for basic standards over time. You can check these more frequently than this interval, and it may save a lot of headaches to do so. 

Moderate Shooters

You’re most likely a moderate-volume shooter if the following is a good representation of you and your habits when shooting an AR:

• Shoot once a month up to 2 times a month

• Shoot less than 500 rounds at each range outing

• Buying bulk ammunition in case loads not by the box.

Here’s a good schedule for moderate-volume shooters for maintenance:

You should clean the following areas of your gun at the paired interval: 

See the above content for the 250-round and 500-round count cleaning regimen. 

You should expect to have the following parts and be checking for obvious signs of breakage, loss in fitment, spring tension and general wear at the paired interval and the listed locations on your firearm:

See the above content for the 2500 and 5000 round count for basic standards over time. You can check these more frequently than this interval, and it may save a lot of headaches to do so. 

High Volume Shooters

You’re most likely a high-volume shooter if the following is a good representation of you and your habits when shooting an AR:

• Shoot more than twice a month

• Shoot more than 500 rounds at each range outing

• Ammunition doesn’t matter as long as it goes bang - “If it seats it yeets”

• You have dark, powder and lead-covered hands after every range session, and you smell like smokeless powder at least 3 days a month

Here’s a good schedule for high-volume shooters for maintenance:

You should clean the following areas of your gun at the paired interval:

Check your AR every 500 rounds. Period. If it’s running fine, then look for obvious debris or safety concerns. If it’s getting sluggish, clean it and lube it - properly.

You should expect to have the following parts and be checking for obvious signs of breakage, loss in fitment, spring tension and general wear at the paired interval and the listed locations on your firearm:

The above regimen for 250 - 10,000 rounds is a good roadmap for high volume shooters. You may not need to check so often; there are a lot of factors that can positively affect how often you have to clean. Note, however, that there is not a substitute for a safety check. You should be checking for safety concerns at least every 250 rounds as listed above.  

Your high volume shooting may require more frequent checks for safety and maintenance, especially as the round counts go above 10k - 12.5k. This is a good time to check hard wearing components for replacement.

Even the best firing pins; springs and bolt faces will show significant usage wear at this point. That doesn’t mean it’s an unsafe endeavor to keep using them, but it does mean you should be aware that you need to keep an eye on wear and performance going forward on those parts. 

An Important Note About Heat and Rate of Fire

When you accumulate round counts at the higher end of the spectrum it means that you need to service and look for safety and maintenance problems more frequently. This is even more true when you are shooting 50 rounds at a time as fast as you can fire and going until your barrel is smoking from heat and oil is starting to creep out of the metal’s pores.

If you are frequently firing more than 100 rounds in less than a few minutes, you will need to monitor your gun for wear and damage and safety concerns more frequently. 

A total of 450 rounds fired in close succession can kill a barrel if you do it the wrong way. 750 can melt gas system parts. If the gun is getting too hot to hold you may have already gone too far. 

The best practice is to let the gun rest every 250 rounds if possible, with a basic visual safety and maintenance check. Letting the rifle cool down for fifteen minutes can ensure it has a long life. 

If you are shooting with a suppressor, these numbers should be adhered to strictly. The excess heat on the end of the barrel when you get into rapid firing of more than 350 rounds can be damaging to component parts.

This is especially true of the suppressor, muzzle exit; chamber, bore and gas system, as well as the bolt face and carrier gas tube interface. 

In the end, you will need to maintain basic common sense when running your firearm to ensure it gets the longest life out of components and you remain safe. That’s stating the obvious of course, but a little care and maintenance can go a long way, and it’s better to be safe than sorry, generally.