The M16, M4, AR15 family of carbines are highly reliable when maintained properly. However, I still see consistent issues with proper cleaning and maintenance of these firearms. Here are a few general guidelines to follow to ensure reliable function and lifetime service from your carbine.

Quick Strip & Clean

Attempt to field strip and quickly clean your carbine after each shooting or range session. Even if this means you only have time to degrease the bolt carrier, bolt face and clean out the chamber and bore. This will go a long way toward maintaining reliability.

Less Is More: AR15 M4 M16 Carbine Maintenance

Common build-up point on the bolt. NEVER stretch out or compress gas rings.

Try soaking small parts such as the charging handle, bolt carrier, bolt, and its small parts in a Tupperware container of Hoppe’s #9 overnight. This will make cleaning these small, hard-to-reach surfaces much easier and save time and trouble in the long run.

Less Is More: AR15 M4 M16 Carbine Maintenance

Try soaking small parts overnight making cleaning easier

Attempt to fully field strip, inspect and thoroughly clean your firearm after every 3000 rounds. Note any “witness marks” or where metal has rubbed on metal wearing away finish. These are important lubrication points.

Critical Components

Keep a close eye on components that are critical to the proper operation of your carbines such as the extractor and spring, ejector and spring, gas rings, firing pin, and buffer spring. It is a good idea to have backups for all of these essential parts in a range bag or kept at home.

Inspect the extractor claw making sure there are no cracks where the metal is thin or chips and that the claw is not filled with carbon or debris.

Less Is More: AR15 M4 M16 Carbine Maintenance

Clean extractor claw trench of any debris and visually inspect for cracks or chips.

Bolt Carrier

When lubricating remember that “less is more”. Your bolt and carrier do not have to be soaking wet. Extra lubricant will attract dust, dirt, and debris when firing your carbine. A light coat or sheen is all that is needed. Look closely at the gas key on top of the bolt carrier and make sure it is still tight. “Staking” the gas key is a method of¬†ensuring the gas key doesn’t loosen. This requires a special tool that most armorers or decent gunsmiths should have.

Ar15 Gas Key

Verify the gas key is tight.

Less Is More: AR15 M4 M16 Carbine Maintenance

Gas Key Should be “staked” to make sure it doesn’t loosen.

Less Is More: AR15 M4 M16 Carbine Maintenance

Bolt carrier lubrication points and witness marks. DO NOT lubricate bolt-face.


Charging Handle & Latch

Make sure the charging handle is not bent. Lateral stress is put on the charging handle during aggressive cycling and over time they will bend and the finish will wear on one side creating witness marks. Verify the charging handle release latch is functioning properly.

BCM Gunfighter Charging Handle

Charging handle lubrication points: common “witness marks” or silver areas.

Trigger Group

Utilize a q-tip, toothpick, or dental pick to clean carbon or chunks of debris out from around the trigger group. Visually verify the legs of the trigger spring are the same length and not broken.


Clean any build-up or debris out from around the trigger group. Verify trigger spring legs are the same length (red arrows).

Buffer Spring & Buffer

During dedicated field stripping remove the buffer spring from the receiver extension tube and inspect. Remove the buffer from the spring and degrease along with the spring. Lightly lubricate the spring before replacing the buffer and spring into the receiver extension tube.

Spike's Tactical Buffer

Clean and lightly lubricate buffer and buffer spring.

Cleaning Tools, Solvents & Lubricants

Listed in the order I use them. No fancy cleaning tools are necessary to maintain a carbine. Field expedient items found at any small mini-mart or box store can be utilized for 99% of carbine maintenance. However, good cleaning kits such as those manufactured by Otis are a good investment and can make the job easier.

  • Paper towels
  • Toothpicks
  • Q-Tips
  • Green Scouring Pad
  • Small screwdriver
  • Dental pick
  • Brass & nylon brush
  • Pipe cleaners
  • Bore Snake
  • Chamber brush & rod

Degreasers and Lubricants

There are numerous degreasers and lubricants available on the market today ranging in price. Over the years I have tested and used pretty much all of them. The best degreaser I have found is Mil-Comms MC25. For lubricants, I use and recommend Mobile One motor oil found at any box store. If these motor oils work in high-performance vehicles and motorcycles they will certainly work in a carbine. A single container of Mobile One ($4) will last several years. Use sparingly, apply a very small amount to the tip of a finger and then apply to common lubrication points.

  • Mobile One 30W
  • MC25 Cleaner/Degreaser (Milcom)
  • Hoppe’s Elite (spray bottle)
  • Hoppe’s #9 bore cleaner (for soaking parts overnight)
  • Lubriplate (or other white lithium greases, see boating departments)
  • Gunk White Lithium Grease
  • TW25b or Tetragrease (grease with Teflon suspensions from Milcom)

Cycle of Operation

Finally, learn and understand the “Cycle of Operation” of your carbine: Feeding, Locking, Firing, Unlocking, Extracting, Ejecting, Cocking, Chambering. Understanding this cycle will aid in recognizing and diagnosing any malfunctions or problems experienced while firing.

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  1. Great article, Chris. Wonder if you use a bolt carbon scraper tool or if just the overnight Hoppe’s soaking is sufficient?

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