When you first start learning about silencers, one of the terms you’ll start seeing tossed around is ‘blowback’.
In this article we’re going to explain:
- What blowback is
- How different weapons are impacted
- How to prevent it from causing problems
Keep in mind that many modern suppressors are specifically designed to reduce blowback; so, if you’re worried about it give us a call and we’ll help you select a model that will fit your needs.
What is Blowback?
In order to illustrate the concept, let’s look at an extremely common semi-automatic weapon: the AR15.
When you pull the trigger on your AR15, you’ll set in motion a series of events – which can be simplified into these steps:
- The powder is ignited – which creates the pressure required to send the bullet down the barrel (with gas expanding behind it)
- Once the bullet passes the gas block (which is typically under the front sight post or rail), some of the gas is redirected back through the gas tube and into the chamber
- The gas pressure entering the chamber allows the bolt to unlock and cycle – which loads the next round into the chamber
The gas that goes back into the chamber is called ‘blowback'; and, hopefully it’s clear that blowback is required to make your AR15 operate correctly.
Keep in mind that, although many people tend to focus on the gas coming back through the gas tube – a lot of gas also comes back through the barrel itself after the bolt is unlocked.
In this example, imagine adding 6″ of additional barrel length without moving the gas port – and you’ll start to get an idea of how blowback can be bad.
As the barrel length is increased, so is the amount of pressure sent back through the gas port & barrel. This increased gas pressure will cause the bolt to unlock a bit earlier and cycle faster. It will also force more gas into the chamber as the weapon is cycling.
Now, just start thinking of your suppressor as a barrel extension (which is exactly why you’ll get a velocity boost when using a silencer). Do you see why blowback comes up so often when talking about silencers?
How are different weapons impacted?
At this point, let’s move away from the AR15 example and start focusing on different styles of weapons:
Single Shot Weapons (such as bolt action, lever action, break open, etc…)
Weapons that are cycled manually aren’t impacted by blowback at all. In those cases, adding a suppressor won’t have any negative effects – and you’ll benefit from reduced sound, increased accuracy & range, and reduced recoil.
Gas Blowback Weapons
The AR15 we already talked about is a common example of a gas blowback weapon – but there are many others.
In this case, the additional blowback can cause several issues:
- The faster bolt speed will cause the carrier & bolt parts to wear out faster – although this typically isn’t noticeable for most users.
- Since the bolt is cycling faster, it’s possible to actually outrun the spring in your magazine. (This is often referred to as Bolt-Over-Base.) In this case, your weapon will either jam or lock up on an empty chamber.
- The weapon will get dirtier faster since there is more gas in the chamber.
- You’ll generally smell more gas; and, depending on the weapon, may feel it blowing into your face & eyes as you shoot.
Fortunately, there are several easy ways to get the blowback levels back to optimal levels.
Recoil or Piston-Based Weapons
There is a lot of confusion about using a suppressor with piston weapons. The biggest source is when people assume all the blowback is coming through the gas tube of gas blowback weapons.
As we already mentioned, a portion of the blowback also comes through the barrel itself; so, most of the same problems that occur with Gas Blowback designs will also happen with piston & recoil designs.
How can you prevent too much Blowback?
Although we’re going to focus on the AR15/10 style weapons here – these same concepts will apply to pretty much any gas-operated firearm.
Before going any further, if you’re not having negative issues – don’t try to solve a problem that doesn’t exist. If you’re having one or more of the issues described above, try these simple suggestions:
- Use a heavier buffer – This will slow your bolt back down and will solve most cycling problems for just a couple of bucks
- Try a Gas Buster or Griffin SN-ACH charging handle – If you want to reduce the amount of gas escaping around the charging handle, then this is a great accessory!
If you want the ultimate solution, then I’d recommend the Gemtech Suppressed Bolt Carrier (also availabe for an AR10). These bolt carriers work wonders and are adjustable so your weapon will run optimally in either suppressed or unsuppressed mode.
(But… Why would you run unsuppressed?)
For Piston-Based Weapons, most modern designs include some type of suppressed adjustment. This adjustment is there specifically to tune the weapon when running a suppressor – and it’s easy to use in most cases.
For Recoil-Driven Weapons, you generally won’t have any serious problems; but, if you do try using a slightly heavier recoil recoil spring.
At the end of the day, blowback isn’t a huge issue on most weapons. If you do run into it, try going through some of the solutions listed here – or give us a call and we’re happy to help.