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How to DEEP Clean a Gas Shotgun | Tips and Tricks!

how to Apr 13, 2023
how to deep clean a gas shotgun


If you have a shotgun, cleaning is a must.  Cleaning a shotgun can be a tedious and messy job, but it doesn't have to be. Steve shoots a lot and therefore cleans a lot. Over the years, he has tried many different methods to find the easiest and most effective way to clean a gas-operated shotgun.  So today, we're getting down and dirty clean with the gas-driven Mossberg 940 Pro, showing you how you can easily and effectively clean your gas shotgun for top performance in the field as well as a longer lifespan.

Let's start from the beginning - first, we should always check to ensure the gun is fully unloaded before disassembling it.  We know it should be unloaded already, but it is always best to double-check.

Put on some latex gloves. This keeps chemicals off your skin and makes cleaning up much easier. If you like the smell of gun cleaner on your hands for the next day or two, you may want to skip this step.

Next, we get all of our cleaning products in order. We have many of them, so we'll link them below as we mention them. In full disclosure, Otis Technology and Shooters Choice are partners with Target Focused Life. We love their products, and Steve has been using their products for many years, but use whatever works best for you. If you do purchase any of the Otis or Shooter Choice products, use code "tfl15" for a 15% discount.

1. BREAKDOWN - Ensure you have adequate room to work with, as gas shotguns have more internal parts to take apart and manage. We'll be taking this 940 apart all the way down to get all the parts and hard-to-reach spots clean.

2. PISTON - Once the gun is apart, the first thing is to get the piston soaking in cleaner. the piston is the heartbeat of a gas shotgun and it gets a lot of carbon buildup. Give the piston an initial spray down and let it soak in the cleaner. Spraying the piston over a small bowl or cup to minimize the mess. We use Shooters Choice Shotgun and Choke Tube Cleaner for this step. MC7 works great too. 

3. BOLT - Do the same treatment on the bolt as with the piston and set it aside.

4. MAGAZINE TUBE (OUTSIDE) - With the Shooter's Choice still in hand, hold the body of the shotgun over a large, empty garbage bin, and spray down the mag tube. We suggest doing these larger parts over an empty bin like this with a garbage bag in it to capture all the extra chemicals that will drip into the bag, rather than onto my workbench or the floor. Start with a fresh bag in your bin to prevent any pieces from getting really dirty if you were to accidentally drop something in the garbage. 

5. RECIEVER - At the same time as the mag tube, spray inside the receiver to get a really good initial coating that will drain out any larger debris. The foaming action of this Shooters Choice Shotgun Cleaner does a really good job of getting every corner of the shotguns internals 

6. BARREL - Let the mag and receiver sit and soak over the garbage as you spray down the barrel, and into the trash. Be sure to hit the port on the barrel that houses the piston as well as the part of the barrel at the back of the barrel that goes into the receiver.

7. CHOKE TUBE - We'll discuss my favorite trick for cleaning the choke tube later but for now, hit it with the choke tube cleaner and let it sit in the bowl with the piston

8. TRIGGER GROUP - Just like the barrel and receiver, I'm going to give the trigger group an initial spray down over the garbage 

9. MAGAZINE TUBE - Now that the mag tube has been soaking a while, go back to it and give it an aggressive scrub down with a scotch-brite pad. I like to pair this with one of those softer gun-cleaning-specific pads that often come in a gun-cleaning kit. These mag tubes see a lot of carbon build-up and require some extra love to get shiny again. Because of this build-up, I switched to another one of my favorite products: Once you've scrubbed the carbon buildup loose, spray it off with The Shooter Choice Quick Scrub. The Quick Scrub is one of our favorite products to make cleaning much quicker. 

10. RECIEVER - Scrub out the receiver thoroughly with a nylon brush and then spray it out clean with The Shooter Choice Quick Scrub. This combo gets rid of smaller debris like a charm. 

11. BARREL - The barrel can be a bugger to get super clean. We like to use a combination of techniques to get it clean starting with a copper brush to break up any buildup. Then, put a small cleaning kit rag over the copper bristles to make the pass air-tight. This may bend bristles over time, but we've found it super effective. There are plenty of attachment options that OTIS provides for cleaning the inside of the barrel. I basically repeat this process until I'm certain that I've pushed all the debris out. I'll also use the nylon brush on the barrel to make sure that the gas port that houses the piston is free of junk. On this particular cleaning, I probably did a pass of the barrel 5 times. To finish it off and make sure it is squeaky clean, it with quick scrub, and do another pass with the brush. 

12. BOLT/PISTON/TRIGGER GROUP/CHOKE TUBE - Now that the components of my bowl have been soaking, I'm going to perform the same nylon brush-and-quick scrub combo that I used for the receiver to work out all the smaller debris. 

13. CHOKE TUBE - Your choke will get a lof plastic buildup from the plastic wads. We can't forget to give the choke tube a good clean. Plus,  If the choke is left in the shotgun too long, the choke tube will eventually become frozen to the barrel threads - not good. Before you put the choke back in use the Otis Choke Tube Lube on the threads. Then, mount a copper brush to a drill and spin it inside of the choke to break off any internal build-up. Ideally, you'd do this before working on the barrel because all of the debris could fall back into the barrel. You can do this step by hand but having a drill will make your life much easier.

14. LUBRICATION - Once we're happy with all of our clean parts, we have to lube the shotgun to ensure that it will continue to run smoothly. Our favorite product for this is the Otis Dry Lube. Go through and hit every moving part with this product (trigger group, receiver, barrel flange that connects to receiver) We recommend lubricating with the gun disassembled to ensure you're hitting all the nooks and crannies. Once lubricated, give the parts a quick wipe-down with a soft kit rag to ensure you don't have too much excess lube. Yes, too much lubrication can cause problems.

15. ASSEMBLY - We're ready to put this 940 back together! Put the shotgun back together, but wait to put on the forend grip.  Wipe down the barrel area that will be covered by the forearm. We love The O85 Firearm Wipes for this final task. Throw on the forend and then wipe down the rest of the shotgun. The 085 Wipes are a CLP so the clean, lubricate, and protect in one pass.


That's a wrap on this quick inside look at what keeps TFL shotguns running for a long time! Let us know your favorite techniques for shotgun cleaning on the TFL Community. See ya!

Whether our targets in the field or our targets in life, we will only hit what we are focused on, so live the #targetfocusedlife 

Stay Target Focused,


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