Suppressor 101: Understanding Rifle and Pistol Suppressors
This article will review the different options to mount a suppressor, bullet velocity, caliber size, and adapters. I will also discuss how suppressors work and point you to a few good sources of information. Let’s get started!
First I will cover a few terms that will be thrown around in this article.
“Silencer” or “Can” – both of which are terms that are used interchangeably with the term suppressor, they are one and the same. The suppressor is the most accurate term but the ATF actually uses the term Silencer in the law and Can is more of a slang term.
“Walking” or “Walk off” – Refers to the suppressor becoming unthreaded from the barrel when a person shoots. The suppressor can come loose and cause baffle strikes.
“Baffle” – A mechanical piece of the suppressor used to guide gas/pressure to the desired direction. (more to come on this)
“Rubber” or “Wipe” –Originally, this was intended as a device that helped maintain a gas seal with the bullet and the suppressor. Modern suppressors are built with close tolerances and no longer use or need this seal.
“NFA” – NFA is a reference to the National Firearms Act that was enacted in 1934 and among many other things provides restrictions on the transfer, possession, and registration of silencers. This is the law that requires you to buy a $200 tax stamp while transferring a silencer.
“Title II” – This is the section of the NFA that specifically talks about silencers.
“Class 3 Dealer” – This is an FFL license designator that allows the FFL holder to transfer Title II NFA items. i.e. Class 3 FFL licensee.
Now that we have the terms out of the way, I will be referring to a suppressor as a can from this point forward. In order to mount a can, there are three different options on the market.
Welded or Integrated – Welded and integrated cans are less common, as they are usually used in specific applications. In other words, the can is attached to the barrel permanently making the barrel as a whole an NFA item. Most commonly you will see these types used when the design intent of the weapon is to provide a more effective design in a smaller overall length. An advantage of this mounting type is that once install/built correctly there is very little chance of the can coming out of alignment with the barrel and causing a baffle strike. Typically I would avoid welded or integrated cans as it limits your ability to swap to different rifles or handguns.
Direct Thread (DT) – DT allows a user to screw a can to the end of the barrel (muzzle). These are fairly common, especially on handguns. The primary disadvantage of DT is that they have a tendency to walk off, which requires the shooter to ensure that can is tightly attached to the muzzle while shooting. If you have put a few rounds through the can you will find it to be very hot and difficult to snug. For this reason, some manufacturers use left-hand threads for attaching the can to the muzzle. Another issue to be careful of with a removable can is to ensure that the can is in alignment with the axis of the bore. If the can gets out of alignment your chances of a baffle strike increase and the suppressor barrel unit can become dangerous.
Quick Detach (QD) – QD is becoming more and more popular for weapons other than pistols. In fact, most manufacturers have started focusing primarily on creating flash suppressors/breaks that will act as both a QD mount and muzzle device. QD allow the user to easily add or remove a can and securely fasten it to the barrel for use. QD eliminates issues that direct thread suppressors can have as such as backing off of the threads during use. As with direct thread on cans, it is important that the mount on the barrel is aligned correctly with the axis of the bore. Most QD suppressor systems also allow the user to reattach the suppressor in the same way each time which results in a more consistent point of impact shift between reattaching cycles.
This is another topic that occurs quite often in the forums. The simple and quick answer is that a suppressor will have little impact on the velocity of a bullet. I would go into greater detail, but Nick over at TheTruthAboutGuns.com has already done a great job. Check it out here. That being said there are a few integrated suppressor systems that are designed to vent firing gasses early in the barrel to prevent the bullet from reaching supersonic speed.
Another important factor of bullet velocity is that bullets moving faster than the speed of sound (supersonic) will still make noise. The suppressor is designed to act the same way a car muffler does and control/quiet the sound of the expanding gasses out of the front of the barrel. It cannot do anything about those other sounds that the weapon in making whether that be the sound of the action or the sonic boom the bullet is making.
You can fire supersonic rounds through a suppressor with no problem and the suppressor will do its job and you will hear considerably less noise when you fire, but the crack of the bullet will still happen. In most pistol calibers it is possible to buy subsonic loads to work with a suppressor but most rifle calibers are not designed to be subsonic. Specific rounds such are the 300BLK were designed to be suppressed and can be found in subsonic loadings. If you are looking at a cartridge and not sure whether it is subsonic you can look at the advertised bullet speed, anything below 1,100 fps will be subsonic.
Since suppressors function by controlling expanding gasses they are more effective when they have more volume to deal with the expanding gas. The problem is where the volume comes from when you are attaching a device to the end of a muzzle. There are really only two directions that you can go, wider around or further out. This is where the benefit of integrated suppressors lies, suppressors that are integrated with the barrel can actually use a shorter barrel and more volume around the barrel to be more effective without adding more length to the barrel.
For all other suppressor types, there is usually a tradeoff of how effective the sound suppression is with how unwieldy the suppressor will make the gun. Unfortunately, physics will not let us create a suppressor the size of a pill that will make your .50 BMG whisper quiet. When deciding on a suppressor size is an important factor that is usually determined by a tradeoff of your priorities in a suppressor. If absolute noise suppression is your number one priority be prepared for a very large and long can on the end of your rifle. But if you only want to bring down the size of your gun, you can get a pretty effective can that is a reasonable size.
Point of Impact (POI) Shift
The point of impact will shift with the use of a can, due to the change in weight and harmonics of the barrel. The good news is that at close range it will not be noticeable. As you increase your shooting distance, you will start to notice a major difference. Using a quick detach attachment type that is indexed helps ensure that the can is always fitted to the barrel in the same way and in most cases will a result in a consistent shift in the POI that is repeatable between removal.
Caliber Sizing Explained
Probably the most common question that comes with purchasing a can is: “What size or caliber suppressor do I need and will it work for other calibers?”
Lucky for you, the answer is fairly straightforward. Most cans of a larger caliber will work for a smaller caliber. For instance, if you buy a .30 caliber can, it will work on 5.56. You can even buy a .45 caliber and use it on 5.56, but there are a few impacts to such a large caliber drop. It is important to know what pressures a can is rated for especially if you plan to use your can with a caliber other than what it was designed for.
This is especially important if you are using a can with a diameter for a .22 or .30 caliber due to a large number of calibers that use the common diameter bullet. You should never use higher pressure round in a can that was designed for a lower pressure.
Common examples to be aware of are cans designed for .22LR should not be used with .223 or 5.56 due to the much higher pressures and volumes of gas. Common .30 calibers that you should be aware of are 300BLK .308/7.62 and 300 win mag. While all of these are common .30 caliber rifle loads, all 3 produce varying levels of pressure and volume of gas. Most cans designed for 300BLK these days are also designed for use with .308/7.62 but very few cans are designed for .30 caliber loads above that. So, just because it fits does not mean it is safe. Always verify with the manufacturer before you go to the range.
Impacts of Large Caliber Can on Small Caliber Weapon
- Will not perform as well due to the extra space around the bullet traveling out of the can. In reality, it will have little impact as the bullet will be surrounded with excess gas.
- Will be louder than a can designed for the specific caliber.
- Depending on the caliber used, it could cause more fouling or led deposits to build up in the can requiring more frequent cleaning.
First Round Pop – This occurs when the first round is fired through a cold can. It is actually the oxygen in the can combusting. It can actually be overcome by putting a teaspoon of water into the can from the muzzle lock end.
Baffle Strike – This usually results in a catastrophic failure of the can and occurs when a round actually hits one of the baffles inside the can. It can happen due to multiple reasons, but if you keep an eye out for any bulge on the can it will help you identify an issue early.
Water – I talked to this above in First Round Pop, but if you put a teaspoon of water in the muzzle lock end of the can it will actually increase the noise reduction.
Revolvers – Unfortunately, you cannot use a can on a revolver. Due to the design of a revolver, the excess gas/pressure escapes between the cylinder gap and the barrel.
Using a Can on a Gas Driven Action
Due to the fact that suppressors control the expanding gasses coming out of the muzzle, they also increase the amount of time that higher pressures are in the barrel and action after the bullet has left. The most noticeable effects are higher pressures in a gas operated action and more exhaust gasses leaving out of the breach when it is opened. Gas operated rifles are usually either piston powered or direct impingement.
Neither of these systems benefits from the increased pressures that a suppressor brings. The higher pressures can bring higher bolt velocities, dirtier actions and even more, gas in the shooters face. This can all combine into a rifle with a shorter maintenance window and shorter round counts on parts before they need replacement. Many manufacturers make specific gas blocks that can be adjusted to help account for this but that can also lead a whole host of problems as the action is tuned to work with and without a suppressor.
A question that comes up in forums quick often is whether you should use a can on a direct gas impingement rifle (i.e. AR-15) or a gas piston rifle (i.e. ). In practice, you can use a suppressor with either action without failure. It is recommended that you use a PRI gas buster charging handle or make a barrier with sealant on your charging handle to help prevent the excessive gas from blowing into the shooter’s face when using a suppressor with a direct impingement system.
Rifle vs. Handgun
Cans designed for handgun calibers are usually slightly more complex than ones built for a rifle. This mainly had to do with the action of the intended host weapons. Most pistols use a delayed blowback design that when paired with a standard suppressor result in the pistol not ejecting the spent cartridge and feeding a new one. In order to prevent this problem engineers added a buffer to the suppressor to help drive the action. Cans designed for rifles and most .22 caliber actions do not include this buffer system. Most manufacturers offer piston systems that mate to specific handguns along with fixed spacers for use on host guns that do not need the assistance.
The legal Issues Involved
It is legal in most states to possess a suppressor but you do have to file a little extra paperwork and pay Uncle Sam his cut for the privilege. You can verify if your state is among the free on the American silencer association webpage here. TheARGuys highly recommend that you get some quality legal advice before you spend your hard-earned money on a suppressor. There are a few important things you need to be aware of in order to take possession of a suppressor. Depending on how your paperwork is filed you will usually have a few months to wait and stare at your suppressor at your local class 3 FFL before you get to bring it home. Remember to always have your paperwork with you when you have your suppressor so you don’t end up on the wrong side of the law.
The guys over at The Silencer shop have a good article on the three ways that you can possess your suppressor, here. Hint, we recommend a Trust.
I could spend hours on talking about this topic and suggesting different makes, models etc… In reality, you just have to determine what gun or guns you plan to use a can on and determine if size or sound is more important. Right now there are a lot of good companies making great products and we expect to see some cool stuff in the next few years. Stick with a manufacturer with a good warranty and the features that you want. As with most of these items buy once cry once.