Oil Filter As A Silencer: Is this Legal? Does It Really Work?

oil filter as a suppressant on a handgun

What is “Solvent Trap“?

The solvent trap is a gun cleaning system designed to collect cleaning solvent for effective disposal. The solvent trap is characterized by a cup, also called a divider, used to collect the by-products produced during the cleaning process.

The oil filter suppressor is sold as a “solvent trap”. They are being marketed as a cleaning device to catch solvents poured down a barrel. Along with the filters, many online companies also sell adapters to make the suppressors work more efficiently. People can legally purchase Oil and Fuel filters from Dooxi, but the downside of these devices is the fact they still require the same paperwork, tax stamp, background checks that standard suppressors require. While these suppressors are most likely cheaper than the standard suppressor, they require individuals and those with Gun Trusts to go through all of the same steps for an imitation product.

Most people may think that an oil filter’s only potential is to remove contaminants from engine oil, transmission oil, lubricating oil, or hydraulic oil. However, solvent traps and oil filters are now used as backup gun suppressors. The good news is that it is cheaper than the actual suppressor and people can do it by themselves at home.

It’s possible to spend $55 around for an oil filter suppressor compared to a standard suppressor for about $600. Also, you will need to pay the extra $200 tax stamp if you want to be legal.

fuel filter

How is the oil filter used as a suppressor?

First, you need to choose your own oil filter and threaded fitting with barrel adapter to fit the mouth of the oil filter. The tricky part is always making sure you match the correct thread.

Using the muzzle brake adapter, thread it into the end of the barrel. This adapter will change the thread of the barrel and “fit it” to accept the thread of the oil filter.

About oil filter which is full aluminum build only good for rim fire cartridges and more importantly u NEED to fill out a form1 and pay the tax stamp and then wait for that to come back approved then and only then can you drill to fit the caliber intended note.. the can will also have to have the serial number engraved onto it must match exactly to the one you created on the form 1 paperwork nice try atf I follow the law and have done my homework.oil filter silencer

Don’t forget that you also need to pass background checks and pay the $200 tax stamp before you can start building your suppressor.

Do not attempt to machine parts, drill holes, or otherwise construct unregistered suppressors. Otherwise, you may go to jail. In some states, suppressors are illegal, so part of the process is to know whether your state is friendly to suppressors.


How to make oil filter silencers?

The oil filter consists of a perforated steel sleeve and is surrounded by soundproof filling elements enclosed in a steel shell.

For example, there is a second layer of metal sheet under the top of the oil filter, which provides a good double baffle for bullets to pass through. Looking inside the oil filter, you must make sure that there are no brackets or fixtures at the top that might interfere with the passage of bullets.


  1. Glue smaller bushing into Insert bushing into coupling larger bushing and tighten band clamp.
  2. Make four slits in coupling.
  3. Fit adapter onto the bottom of the oil filter and install on a weapon.


  1. Wrap oil filter with enough layers of tape to ensure a tight fit in a cardboard tube.
  2. Friction fit oil filter into a cardboard tube.
  3. Install on the weapon.

How to make your DIY oil filter suppressor legal?

After learning how to use an oil filter as an alternate suppressor, you have to know the regulations. DIY a suppressor is not difficult, but building your own suppressor requires you to follow the same process as you would to make a registered and legal short-barreled rifle (SBR) or short-barreled shotgun (SBS). You need an approved Form 1. You have to pass background checks and pay the $200 tax stamp before you can start building your suppressor.

Do not attempt machine parts, drill holes, or anything else that may be construed as building an unregistered suppressor. Otherwise, you may end up in jail. There are also states that prohibit the use of oil filter suppressor. Thus part of the process is needed to be found out if your state is suppressor-friendly.

These are the 42 states that allow private ownership of suppressors:


Keep in mind that these alternative suppressors still require the same paperwork, tax stamps, and background checks as standard suppressors.


As for full aluminum build oil filters or fuel filters are only good for rim fire cartridges and more importantly u NEED to

  1. fill out a form1 and pay the tax stamp
  2. and then wait for that to come back approved
  3. only then can you drill to fit the caliber intended note. the tube will also have to have the serial number engraved onto it must match exactly to the one you created on the form 1 paperwork.

Note: Form 1’s are turning around in just a couple weeks these days while Form 4’s are taking almost a year.

They are now using filter components to make silencers to meet the above steps. Probably it is: fill in the form-pay tax-wait for review.

Is it illegal to have unassembled components of an unregistered oil filter suppressor?

“No, this is an oil filter and a metal adapter. This is a “Solvent Trap Adapter” post published on ebay, wish and dooxi, “Solvent trap Adapters are designed to collect the cleaning fluid in the oil filter without causing any confusion! It can only be used for this purpose “. If you use this feature, you may make some homemade suppressors. However, in fact, if you happen to own these parts and do not use them as suppressors, then this is illegal.”

“Even formed 1 it but I made them ship the parts in 2 packages one with core the other with attachment (to different house) (not from this vendor) because in one package it’s usable and highly illegal I also sent atd a copy of what it was for my design and was approved put it all together and had it engraved…….it’s no different then going to the store and grabbing a tube a bunch of spacers and washers and putting it together the key is intent I had no intent to use the product in a illegal way and only assembled (or even had parts in same place) till I was approved to do so.”——From customers who bought oil filters on dooxi.com.

There are still many ways to buy. But if you are still worried, don’t take the risk. Please follow the application steps.

See more fuel filter suppressor.

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