Common Suppressor Malfunctions: Causes, Diagnosis, and Solutions

I love suppressors—they make shooting so much more enjoyable that I find myself limiting potential gun purchases to guns that I can attach a can to. But suppressors aren’t like muzzle brakes, flash hiders, or other muzzle devices; they can affect the function of a given firearm.

Until a few years ago, determining why a gun that otherwise ran fine had issues when suppressed was a matter of delving into countless internet message boards and praying someone had the same issue as you or a kind stranger could offer some advice. Thankfully, that isn’t the case any longer. 

With suppressors' meteoric rise in popularity in the US, hundreds of resources are available for shooters experiencing issues with their suppressed weapons. While all this information is great, it can be overwhelming. So, for your reading convenience, I’m narrowing down a few common suppressor-related malfunctions and their solutions. Below are the four most common malfunctions and how to remedy them.

• Failure to Eject - Spent casing doesn’t leave the gun after firing.
• Failure to Cycle - The bolt or slide doesn’t travel all the way to rear or does so too quickly and the gun needs to be cleared or charged again to function.
• Excessive Gas Blowback - The hot gases produced by firing a cartridge are excessive and travel rearward towards the shooter’s face.
• Poor Accuracy - The Gun performs noticeably worse with a suppressor than without.

Failure to eject is by far the most common handgun malfunction caused by the addition of a suppressor.

The failure to eject refers to a firearm that doesn’t successfully eject a spent casing after firing.

This often leads to a dead trigger and requires a malfunction clearing drill of either a simple tap-rack-bang, or removing the magazine, racking the slide until the casing ejects, then replacing the magazine and charging the weapon.

What exactly causes a failure to eject varies from case to case, but typically it’s a result of the pressure levels or bolt/slide velocity changing.

Think of firearms like internal combustion engines - if the timing is off, the machine may still function less efficiently, and eventually, issues will arise. Obvious symptoms of failure to eject are a spent casing still inside the firearm’s chamber after firing a round, a round stovepiping or being captured by the slide’s ejection port closing before the casing is ejected.

The solution to FTE (Failure to Eject) issues when dealing with a suppressor depends on the gun.

• If a shooter is running a traditional pistol or handgun, odds are the suppressor needs a booster or Neilson Device. These increase the gun’s backpressure to help it cycle with the additional weight of a mounted suppressor.
• The issue is usually gas regulation if we’re talking about a fixed-barrel carbine, rifle, or AR pistol. However, sometimes it can be bad or underpowered ammo. Another common cause is simple carbon buildup. So, before you buy a new ammo or an adjustable gas block or piston, clean the firearm thoroughly and oil it appropriately.

When suppressed, a cycling malfunction, or short-stroking, is the most common malfunction encountered by fixed-barrel firearms like rifles and carbines. This is when the bolt fails to travel fully to the rear position or travels there and back too quickly. This happens in the world of suppressors because adding a suppressor accelerates the bolt or slide to a velocity the gun wasn’t timed for. 

The two most significant indicators of a failure-to-cycle malfunction are the spent casing failing to eject from the gun or the casing ejecting properly, but the next round not chambering. This can be a very frustrating malfunction since the weapon will “feel” like it’s running fine, then you hear a click instead of a boom. Thankfully, the solutions to this issue are straightforward.

The solution to Failure to Cycle is to adjust the gas pressures inside the gun to acceptable levels.

How we accomplish this depends on the platform we’re suppressing.

• Direct-Pingement AR-15 Solutions
  For shooters using America’s favorite rifle, the standard direct-pingement AR-15, the easiest and cheapest solution is to replace the buffer or buffer spring with a heavier one.
  
  Alternatively, an adjustable gas block (or carrier) can be installed and dialed in. The worst solution is to drill out the gas port on the barrel since doing so will negatively affect reliability when the weapon isn’t suppressed.
• Piston-Driven Solutions
  If you’re running one of the new PSA JAKL rifles, carbines, or pistols, then simply adjust the gas block regulator until the weapon ejects consistently and runs reliably. If you’re running something a little more dated, like an AKM or AK-47-derived firearm like the Galil ACE, you’ll need to install an adjustable piston. Although this can be done at home, I would heavily recommend consulting a gunsmith to do it for you, since it can be tough.
• Pistol Solutions
  With a traditional handgun, there are essentially only two reliable solutions to failure to cycle malfunctions when suppressed. The first it the same as with the FTE - install a booster on your suppressor if it doesn’t have one. But if it already has one and you’re still encountering issues, you’ll need to install a stiffer or stronger recoil spring. Companies like Wolff Gunsprings make dozens of variations of each spring type for thousands of different firearms, so you can dial your gun in to whatever your favorite ammo/suppressor is.

Most semi-automatic firearms cycle the action by using some of the hot expanding gas from a fired round. The addition of a sound suppressor increases the amount of gas that flows back towards the shooter’s face. This is because suppressors function by allowing the hot expanding gas of a fired round to dwell or linger inside the suppressor body and cool before leaving the muzzle. 

This happens because expanding gas from a fired round is delayed by a suppressor and travels rearward towards the path of least resistance. This is often just annoying, as it can make shooting suppressed uncomfortable, but the added carbon buildup can lead to a firearm becoming unreliable after a few hundred rounds. Additionally, the increased cycle speed can cause accelerated wear on bearing components and shorten the host firearm's service life.

Again, the solution depends on the weapon platform. For the AR-15, if gas blowback isn’t causing ejected rounds to fly 30 feet from the rifle, then a simple gas-busting charging handle is a sufficient solution. The new handle will redirect the hot expanding gas away from the shooter’s face and outside the receiver. This both makes shooting more pleasant and decreases the amount of carbon buildup inside the gun.

For piston guns, either adjust the gas block if it has a user-adjustable regulator or install one. Suppose a shooter is running a direct blowback pistol caliber carbine like the AKV or ARV. In that case, they’ll need to get either a larger capacity suppressor or one with some variety of flow-through technology.

Adding a sound suppressor typically has a negligible impact on accuracy (unless the gun has a harmonic stabilizer like old Mini-14s), but certain factors can cause issues.

First, I recommend that a shooter check whether or not the suppressor is mounted securely to the firearm. Before doing so, clear the gun and make it safe. Then, with a heat-resistant glove, try to loosen the suppressor by hand. If it has play in it or can wiggle, it’s not mounted correctly. Use a torque wrench or the included tool and tighten according to the manufacturer’s specifications.

Another, more catastrophic cause is a baffle strike which happens when the round hits a portion of the suppressor and deflects. If a shooter is lucky, no permanent damage is done to the suppressor. This is caused by either using a round too large for the suppressor,  an incorrectly mounted suppressor, or a non-concentric bore.

• The best way to check for this is to first clear the weapon, then check the manual for the suppressor. Most manuals (or manufacturer websites) list the permitted calibers for a given suppressor. Never use one that is larger than the suppressor is designed for.
• If you’re using a permitted caliber, next check bore alignment. Again, double-check to ensure the weapon is clear and unloaded. Use a flashlight to shine inside the bore from the ejection port and look down the barrel to see if the bore is unobstructed. If you can’t tell, next you’ll need to use an alignment rod. These are aluminum rods that show how much clearance a suppressor has.
• Once again, ensure the weapon is clear and safe, insert the alignment rod from the muzzle end of the suppressor into the firearm’s barrel allowing it to rest on the bolt face. If it touches the sides of your suppressor then perpendicular to the barrel, there’s an alignment issue. 
• Check to see if the suppressor is securely mounted and not canted. If it’s not, have a gunsmith check bore concentricity. If it’s a bore issue, you’ll have to have the firearm manufacturer replace the barrel with an in-spec one.

While the four malfunctions listed above are the most common, other issues can arise when using a firearm equipped with a suppressor. These normally stem from either bad or underpowered ammunition or worn-out magazine springs. 

• While subsonic ammunition will give the best sound reduction results when running a sound suppressor, most auto-loading firearms aren’t designed to function with it reliably. For these guns, an adjustable gas system is ideal. Another, more permanent solution is opening up the gas system or reducing the recoil spring tension. Still, since both of these solutions will affect the reliability of standard ammunition, I would advise against them.
• As for magazine springs, most shooters don’t realize that M4 (from which the AR-15 is derived) magazines are meant to be disposable. All magazines wear out over time, but most shooters don’t put enough rounds through them to ever notice. Unless you have a costly proprietary or collectible magazine, I recommend replacing them with new ones if they encounter issues. It’s helpful to mark magazines with the number of failures encountered to determine which ones may be problematic. Keep in mind that suppressed firearms cycle at a much higher speed than standard ones, and because of this, the magazine will have to deliver rounds quicker than usual. A worn-out spring that functions fine with an unsuppressed firearm may struggle to feed on a suppressed weapon.

Most modern firearms will run fine out of the box with a suppressor equipped, but specific styles and designs will struggle. It’s easy to get frustrated after waiting for a tax stamp on a suppressor to clear when the gun simply doesn’t work. But there’s method to the madness - take a breath and think about what’s occurring under the proverbial hood, and follow our handy guide, and you’ll have your new quieter gun running like new in no time.

Personally, I would bring a few different loads of ammunition and new magazines with me to the range the first time I tried out a new suppressor. Switching brands or loads may make all the difference in the world. Also, if you’re firing a suppressed handgun, buy the booster or Neilson Device ahead of time; 99.9% of the time, the pistol will need it to cycle reliably. It’s better to have it and not need it, than to be left with a single-shot pistol that frustrates you to no end. If nothing else, subsequent handguns you’ll buy to suppress will thank you when they don’t have any tissues.