Cleaning Your BCG: Keep Your AR Running
February 24th, 2023
6 minute read
The bolt carrier group, more commonly called a “BCG”, is the heart and soul of an AR rifle. To say it is critical to running an AR is an understatement. A BCG gunked-up with carbon and powder residue is a jam or failure just waiting to happen.
It’s a dirty job cleaning AR rifles; some of us tend to put it off until absolutely necessary. That’s usually after a failure to fire (FTF) or failure to eject (FTE) malfunction — one hopefully at the range where all you’ll be is embarrassed at the most. In real-life situations, you simply can’t afford to risk this.
The AR is a combat-proven system that can be remarkably reliable — but they do require care and maintenance. Also, AR rifles do not like to run dry, so if you remember anything about maintaining your AR, remember this — keep the BCG wet with lube.
I’m going to show you two tricks to help you keep your AR running in tip-top shape: The first is how to keep your gun running during extended training when you don’t have the time to field-strip the gun, and the second is how to field-strip to deep clean your BCG. And don’t worry, my methods are not only thorough, they’re also fast.
Quickie Lube Job
This method is to keep your gun running when you don’t have time to strip it down. You can do this method on the tailgate of a pick-up truck, on the bench at the range or simply sitting on the ground.
First, remove the magazine and ensure the rifle is not loaded. Ever notice those two holes in the BCG that are visible when the dustcover is open? Place a couple of drops of lubrication in there. Rub your finger back and forth along the BCG with the excess oil. Hold back the BCG and drop some more oil onto the bolt and into the grooves in the upper receiver where the BCG slides. Hit the star chamber grooves where the BCG locks into. Hold the rifle muzzle down so the oil flows into the cracks and crevices.
Next drop a few drops into the magazine well, making sure the two oil drops land in the groove where the charging slides in the upper receiver or place some lube on the top side of the charging handle. Then with the muzzle pointing down, rack the BCG using the charging handle a few times to spread the slippery drops of oil throughout. That’s it. You are good to go.
For the next few shots after this quick cleaning method, you’ll see that the rifle will puke out some white smoke from the ejection port and a bit out of the muzzle. That tells you the oil worked its way in the dark crevices inside the rifle and it is lubed and working.
Tools of the Trade
You don’t need a lot of specialized tools to clean an AR. The only specialized tool I use is the Real Avid CORE-AR15 tool. It looks like a carabiner and attaches to a gun bag carry handle and MOLLE straps, or it simply fits in a pocket.
I like this tool since it has built-in carbon scrapers for bolt, carrier, and firing pin. It’s designed to scrape carbon from 12 bolt-carrier surfaces. I also like that it has a pick to clean the extractor, which is a critical part of bolt maintenance. I’ve used my EDC folding knife to scrap carbon off the bolt and clean the extractor in a pinch, but I usually end up ruining the knife.
What’s also helpful on the Real Avid tool is the pick to remove the firing pin retaining pin. This pin can be stubborn to pull out when the BCG is gunked-up, and this pick makes it easy to remove it. To clean the bore, I use a pull-through rip cord and a chamber brush. My solvents choice is easy; any CLP like Lucas Extreme Duty CLP will work great.
Give Your BCG Some Love
Again, make sure the rifle is not loaded. Fieldstrip your AR by pulling out the takedown pin and removing the BCG and charging handle from the upper. Separate the upper from the lower by pushing out the pivot pin.
I focus on the BCG first and take it apart by first pressing the bolt into the carrier until it is fully seated, then pull out the firing pin retaining pin. The firing pin can now be withdrawn from the back end of the carrier. To remove the bolt cam pin, rotate the pin 90 degrees and pull it out. Now you can pull out the bolt from the front of the carrier.
Carbon can build up on the firing pin. Use a scraper, like the Real Avid CORE-AR15 tool, to get it off of there. There are three places on the carrier on which you will want to focus. One is the back end of the carrier. Use a tool to scrape the carbon from the inside. The second is to scrape out the front end of the carrier. The third is to scrape the gas tube to remove the carbon. Don’t use a Q-Tip or cotton swab on the gas tube as the lint from the swab can get caught inside and cause issues.
Next, focus on the bolt. The rear of the bolt is a magnet for carbon build-up. I use the Real Avid scraper to clean it off, fast. The tool gets both the outside and inside of the bolt. Run the tab on the tool through the teeth of the star on the front of the bolt. A critical area on the bolt is the extractor. Use a pick to clean the groove in the extractor. Regularly remove the extractor from the bolt to deep-clean it.
With the BCG reassembled, squirt the outside with lube and, in this instance, spread a lot of the liquid along the BCG. Check you charging handle. You may need to run a soft cloth rag inside the groove of the charging handle. Reinsert the BCG back in the upper and reassemble the upper and lower.
Final Function Check
Finally, run a function check to make sure the safety works and the rifle functions as it should. You are now good to go. Keep your BCG clean and lubed, and your AR will keep running for you.
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