What Is A Solvent Trap?

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When cleaning my rifle’s barrel, I almost always forget to place a rag on the muzzle end when spraying gun oil into the barrel, resulting in excessive oil dripping onto the floor. A solvent trap of some kind just never crossed my mind; neither had I ever seen one used until recently. I was impressed!

Solvent traps are specifically made for use during the gun cleaning process to prevent excessive oils or solvents from dripping out of the barrel and causing a mess. The muzzle-mounted solvent trap allows reusable oil or solvent to be cleanly collected or disposed of.

Modern solvent traps can easily be confused with a suppressor at first glance. They, of course, perform two very different functions. Let us find out precisely what a solvent trap is and for what purpose a solvent trap is used. A solvent trap may just be the gun accessory you didn’t even know you needed.

What Is A Solvent Trap

image credit @ kmwhisper.com

What Is A Solvent Trap?

A solvent trap is an enclosed tube-shaped attachment that screws onto the end of your gun’s muzzle and traps solvents used during the cleaning of the gun’s barrel. This sealed cylindrical “can” prevent oils and solvents from dripping onto the floor or working surface when exiting out of the barrel.

Solvent traps are made to catch and prevent oil and solvent from dripping onto surfaces in your workspace. Most gun oils and solvents are sold in aerosol cans, which are handy to use and coat the gun parts well as the oil is expelled under pressure from the can.

The downside of using a pressurized can is that most of the oil or solvent is often blown right out of the other end of the barrel. Particularly so when cleaning short-barreled weapons such as pistols. The oil then ends up on the floor, on your furniture, or anywhere else it might land. The solvent trap is designed to catch the overspray and reduce the airborne vapors.

The solvent trap can be dismantled to access and safely dispose of the solvents and grime generated during the cleaning process.

Are Solvent Traps Legal?

Most modern solvent traps look pretty much the same as a suppressor. The only difference is the absence of an exit hole in the end cap and the hole in the internals baffles. Many countries require suppressors or silencers, as they’re often referred to, to be licensed or registered with the local firearm authority.

Solvent traps are perfectly legal in the USA as they are not suppressors, even though they may look pretty much alike at first glance. Solvent traps are, of course, used to collect excess solvents used during the gun cleaning process, a harmless and safe exercise. Silencers muffle the rapport of a gunshot.

Adaptors or thread protectors, as they’re often referred to, permit the attachment of the solvent trap onto the end of the muzzle or gun barrel in the same manner as a suppressor would attach. Solvent traps are threaded at one end of the tube while the other is sealed. The thread sizes accommodate the most popular barrel thread sizes.

Solvent Trap Materials

Commercially manufactured solvent traps are aluminum, carbon steel, stainless steel, or titanium. Another popular choice for DIY enthusiasts is using an oil filter made for cars. These filters are made from tin and are threaded; thus can be attached to the end of a gun’s barrel using an adaptor of the correct thread.

The oil filter-based “solvent traps” work well enough, but you won’t be winning any prizes for aesthetics if you want to impress your buddies. I think they’re just enormous and bulky, so I’ll personally stay with the commercial versions that are purpose-built for the job.

Some solvents can be particularly harsh on metals if allowed to stand for an extended period. Solvents remove brass and copper from firearm barrels as such solvent traps are not be made from these metals. Ammonia is often the active ingredient in solvents.

Carbon steel, stainless steel, and titanium do not react with ammonia hence their use in solvent traps. Stainless steel and titanium are the best choices of materials as they are strong and last a very long time. Be aware, though, that the bigger the solvent trap, the heavier it will be. Aluminum is the lightest and also the cheapest making it a great choice.

Ultimately your budget will influence your decision when buying a solvent trap as stainless steel and particularly titanium solvent traps are pretty pricey. 

How Do Solvent Traps Work?

Solvent traps attach to the threaded end of the barrel where the muzzle brake or suppressor usually screws onto. The solvent trap consists of a metal tube that is closed at the end furthest from the barrel. The enclosed end is either permanently closed or has a threaded cap that seals the end of the tube.

The muzzle end of the solvent trap is threaded and screws onto your weapon’s barrel in the same manner as a silencer would. The internal components of the solvent trap consist of baffles that are cup-shaped, allowing solvents and oils to run into it.

The design of the internal cups is such that the trapped solvent or oil cannot run back into the gun’s barrel if the muzzle is elevated vertically. Some solvent traps are modular, meaning the length of the tube and the number of cups contained within the tube can be reduced or added depending on your needs.

Being able to store and re-use clean oil or solvent is a handy feature. Some solvent trap models offer end caps specially designed to trap the solvents. The end cap can be removed and closed, storing the solvent for later disposal or re-use.

Once the gun cleaning process has is done, the Solvent trap is removed from the barrel. The solvent trap is then dismantled by unscrewing the removable end of the tube, allowing the solvents to be disposed of responsibly and clean the solvent trap’s internal components.

The Difference Between Fiel (Fuel) Filters And Solvent Traps

International online shopping platforms offer many different types of “solvent traps” that are generally dirt cheap to buy and readily available. They are routinely marketed as Fiel (incorrect spelling) filters, with the description often mentioning solvent trap. The online filters are available at under forty dollars compared to legitimate solvent traps that cost up to ten times or more than that.

The main difference between the primarily Chinese-made solvent traps and the genuine articles is that the internal baffle configuration is pre-drilled with only the end cap being closed and mostly threaded to remove it. The internal baffles are made of a single, often elaborately machined tube that looks more like the internals of a silencer than a dedicated solvent trap.

Genuine solvent trap baffles are not pre-drilled. In the USA, it is illegal to order these “fiel” filters or have one without first completing the Form 1 application and obtaining approval from the FTA.

Firearm owners may be tempted to order the cheap filter online to convert these to a silencer. After all, only the end cap needs to be drilled to enable the bullet to exit. In fact, some of these filters even have a recess marking where to drill the end cap.

From research, we’ve established that obtaining approval through the FTA to own a silencer or suppressor takes up to a year. The Form 1 approval process takes a month, making it tempting to go the Form 1 route and buy a convertible filter online.

We recommend you wait the year and get the proper, purpose-built silencer to ensure you’re not disappointed. In terms of quality, the online overseas products are not built from solid materials, so if you’re tempted to convert a filter to a silencer, be prepared to only use it on relatively low powered calibers up to subsonic 9mm. A 5.56 caliber round destroys the “filter silencers.”

Countries outside the USA are not subject to or governed by American laws; as such unscrupulous retailers will readily accept your order for a fiel filter and ship it to you. Simply placing the order means you’re buying an illegal product, so please don’t do it. Buy local from a reputable distributor and stay on the right side of the law.

The Difference Between C and D Type Solvent Traps

The C and D classification of Solvent Traps relates to the diameter of the solvent trap. Solvent traps are available in many different configurations and sizes to suit most gun calibers. Solvent traps can differ in length from as short as two inches all the way through to ten inches, which is considered large.

Larger caliber weapons will require larger diameter solvent traps to accommodate the larger barrel diameter. Generally, C-type solvent traps have a maximum thread protector dimension of ½ x 28, the standard thread for calibers in the .22LR, 5.56mm, and 9mm in the USA. The D-type accommodates up to 5/8 x 24 thread protectors (also called adapters) for larger calibers.   

As they’re also referred to, the thread protector or adapters are available in various thread sizes when a quality product is chosen. Gun barrel diameters increase along with the caliber so make sure your solvent trap is large enough. After-market adapters are also available, which enables you to use the same solvent trap on different-sized barrels.

When buying additional adaptors, make sure to specify C or D type and buy the same make as your solvent trap to ensure the threads connecting the adaptor to the Solvent trap tube are the same.

Are Solvent Traps Useable On All Weapons?

Most solvent traps require the end of the gun’s barrel to be threaded to attach to the barrel. Fortunately, companies such as “Lethal Eye” and others supply an adaptor threaded on one end and slips over the gun’s barrel on the other end. The adaptor is held in place by grub screws that press up against the barrel when fastened.

Your limitation using the slip-on adaptor would be to find the correctly sized adaptor for your gun’s barrel diameter. Alternately a good gunsmith can manufacture a slip-on adapter to suit your needs.

Pistols in their standard configuration do not have threaded barrels. Secondly, the barrel does not protrude sufficiently out of the front of the slide to enable the barrel to be threaded or to use a slip-on type adaptor. The only feasible choice to attach a solvent trap is to replace the barrel with a longer one, preferably threaded.

Revolvers also pose a challenge in attaching a solvent trap as the barrels are mostly not threaded. Alternately having the outside of the barrel threaded is possible. The first prize would be to find a slip-on adaptor that fits your revolvers’ barrel diameter precisely.

One drawback with a revolver is that the front sight may need to be modified or moved up the barrel to make space for the threads. This process will no doubt require a gunsmith’s intervention.

Shotgun barrels, being of large diameter, are not suitable for solvent traps. Over-under and side-by-side barrel shotguns can definitely not accommodate solvent traps.

Solvent Trap Friendly Barrel Cleaning Utensils

Given that the barrel end of the muzzle is closed off by the Solvent Trap, the traditional pull-through barrel cleaner can not be used with the solvent trap attached. The best option is to use a cleaning rod, working from the chamber end of the barrel.

Solvent traps work well with traditional gun cleaning equipment, such as cleaning rods using the appropriate brushes and jags.


Solvent traps are a great device used to trap and prevent solvent and oil spills while cleaning your gun. The solvent trap is a sealed cylindrical-shaped device that resembles a silencer and attaches to the end of your gun’s barrel.

As oils and solvent are expelled through the muzzle end of the barrel, it runs into the solvent trap and is contained safely for responsible disposal or re-use.  

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