Hop-Up basics: how does a Hop-Up actually work?

airsoft hop-upThese days it’s rare to see an Airsoft replica without a hop-up. In the earliest days of Airsoft many replica’s had no hop-up. Can you imagine how hard it was to hit your enemy? Maybe you don’t because you just started or you don’t know how a hop-up actually works.

A Hop-up applies a backspin to the BB as it’s coming out of the barrel. The combination of speed and backspin give the BB momentum. Instead of just falling immediately down, the backspin, caused by the hop-up, happens in a way that it actually spinning against the force of gravity. That will result in a nice flat trajectory, greater accuracy and long range.  

How does a hop-up actually work and how important is it for your accuracy and range? We cover these topics (and much more) in this article.

An Airsoft hop-up explained

Airsoft hop-up

Source: wikipedia

Now what does a hop-op actually do? Why does an Airsoft replica need a hop-up and how does it effect accuracy and range?

Hop-up stands for “High Operation Power. All a hop-up does is give the BB a backspin to counter the effects of gravity.

What would happen without a hop-up? What is the difference with or without hop-up? What would happen without a hop-up is when the BB’s come out of the barrel they start immediately run out of momentum and dip down to the ground. This way the BB’s are only propelled by air generated in the gearbox.

Airsoft replica’s without a hop-up shoot very little distance. They shoot about 20-30 feet. If you take an Airsoft replica with a hop-up, it will shoot around 75-100 feet.

Range and accuracy

Not only the hop-up makes a huge difference in range. Adjusting them, can make a huge difference too. You may think that the higher the FPS of your replica, the further you’re going to be able to shoot? Well, that’s not the whole truth. The backspin caused by the hop-up is an important factor in your range and accuracy. You will find out later why…

Not only the hop-up is an important factor on range and accuracy. Actually, range and accuracy come from three things:

  1. Consistency
  2. Hop-up
  3. Barrel


These 3 factors make up the entire range accuracy. How do you get consistency? If your replica has a reliable and good quality gearbox. If the gearbox of your replica has a large degree on FPS margins with every shot, that means one shot is coming out more powerful than the other, the spin pattern is different with every shot. How can you be accurate in such way? So the less FPS variation you have the more accurate you will be!

Less FPS variation means more accuracy!


The barrel of your replica may seem not as important as the gearbox and hop-up but it is important to have it right.  Imperfections or a bend in your barrel have also an impact on your accuracy. Well, at least it’s not going to be nearly as accurate…A wide bore barrel for example is not as accurate as a tight bore barrel. One of the upgrades you can do to get a higher FPS rate is to get a slightly smaller bore barrel. But this has more to do with range than accuracy.


Lastly the hop-up. This is where the majority of your range and accuracy come from. Even with an amazing barrel and FPS you probably wouldn’t be able to make it out more than 50 feet…Your BB’s are just being propelled by air without any backspin. So what would happen is our BB’s come out and then almost immediately start to dip because they run out of momentum. The BB first starts to dip slowly and then as it runs out of momentum it dips down exponentially.

Airsoft replica without hop-up

On the image above you see the end of an Airsoft barrel without a hop-up. As you can see the BB’s starts to dip immediately. As you also can see, Airsoft replica’s without hop-up shoot very little distance.

Now what will happen when you shoot with a hop-up? To prevent BB’s from immediately dip down and lose momentum, a hop-up applies a backspin to a BB as it’s coming out of the barrel. And when coming out of the barrel the backspin added to the BB’s provide lot’s of momentum. So instead of just falling immediately (see image above) they’re actually spinning against the force of gravity. The trajectory then looks like a straight line first and when it runs out of momentum it will starts to dip.

Airsoft replica with hop

So the backspin is important and determines the trajectory of the BB’s for the most part. Even if you have an amazing (upgraded) barrel and gearbox, if your hop-up does not act the way it should, you probably be able to make it out any more than say 50 feet. So take your time to learn your hop-up well by service you hop-up or when you’re cleaning the inner parts of your Airsoft replica.

Airsoft replica hop-up disassembly

Most Airsoft replica’s has an one piece hop-up. An one piece hop-up means that the end of where the bb’s are going to feed from the magazine and the part where where it turn an go down the barrel is all one piece. Most M4 and M16 Airsoft replica’s has a one piece hop-up.  Some brands like KWA utilize a two-piece hop-up. You recognize a two-piece hop-up when the part that feed the magazine with bb’s  stay attached to the lower receiver.

For the servicing, it doesn’t matter whether you have a one piece or two piece hop-up. In both cases you have to do the same repairs, maintenance and replacements.

Some Airsoft replica’s are really pretty to break down in order to service the hop-up. For example the G&G combat M4 Machine and the Elite Force M4 These two Airsoft replica’s are one of the easiest ones on the market to break down. You only have to two pins which attach  the upper and lower receiver.

The upper and lower receiver are connected with push pins or with Allen Key. The G&G has a simple self retaining pin which you can easily pop out. Once you split the upper receiver from the lower receiver, you are able to disassembly the barrel with the hop-up chamber attached to it.

Disassemble the hop-up from the barrel

The hop-up exists of a hop-up unit, a hop-up nub and a bucking. Those are the three parts that make your hop-up unit. To remove your hop-up from the barrel you first have to remove the clip on the bottom of the hop-up chamber. Take a flat head screw driver and pry that clip out a little bit.


Once you’ve removed the clip turn the hop up all the way off by turn it back (counter clockwise) so that on the farthest top wheel the bigger tooth  get stuck in the notch. This way you know that your hop-up is all the way off.

Now you can separate the hop-up from your barrel by giving it a eight turn in one direction and an eight turn in another direction. Go ahead by doing this and start to apply a little pull to it. While doing please be careful and not rushing anything. Once the hop-up is almost on the end of the barrel, give it a firm pull to get it off.

Now you have the three parts that make your hop-up unit: the hop-up, the hop-up bucking and the hop-up nub. This nub is connected to the arm on top of the hop-up. Anytime you shoot that arm on top of the hop-up is moving down and pushes the nub a little bit into the barrel and give the BB’s the backspin.

I don’t think that many of you will completely disassemble the hop-up unit by taking off the gears so I will not go in further detail.

So you get your hop-up off from your barrel. And what did you see?

The hop-up explained

On the image below you see a section of the hop-up chamber. I made this drawing by myself so forgive me if it looks a bit ugly. Anyway, I want to show you how a hop-up actually works.

As you can see on the image above, the hop-up is right above the magazine. In front of the bucking is where your gearbox is and all the air is coming from.

The end of the barrel, the side where is a little window cut into the barrel, goes into the hop-up. Around the end of the barrel you see a blue rubber piece. The dotted lines you see inside the hop-up is the end of the barrel that goes into the hop-up unit. So that rubber piece is called a hop-up bucking. That hop-up bucking has a tooth inside. When you put that hop-up bucking place that little tooth inside hangs down out of that “barrel window” that is cut into your barrel when your hop-up is engaged.

What happened when your hop-up is engaged? Well, on top of the hop-up unit you see a lever with some kind of nubbin at the bottom. That hop-up nub pushes down into the whole chamber and pushes the bucking – that sits around the barrel – slightly down. So the bucking ends op with a little bulge at the top. As the BB travel down past that bulge, it causes friction. And that friction guys… that friction causes the backspin of the BB.

Other functions of the hop-up bucking are:

  1. It handles all of the air seal that’s coming from the gearbox.
  2. When BB’s travel from magazine into the hop-up chamber, there is a little knurling on the end that hold the BB’s. So the BB’s are held against against sort of lips on the end of that hop-up bucking (on the gearbox side) until the piston pushes it into the barrel.

I hope you get an idea now of how a hop-up is working and what it actually does. It’s a complex part of your Airsoft replica but also very essential. If your hop-up is not properly adjusted, your accuracy will immediately went from good to very bad!

Airsoft hop up problems

The most common hop-up problems are:

  1. Your bucking rotates
  2. The bucking wears out
  3. Spring on the arm (lever) does not release

Somehow the bucking manage to turn itself sometimes. Even if you manage to put it on the right way it happens… How do you know when your bucking rotates itself? When you notice a bulge in the hop-up bucking you know that the bucking is not in place.

What next? First take that bucking off. Next realign that ridge and place it on so that it’s smooth all the way around. When doing this, you will find a ridge on on the bottom of the bucking and one teeth an the top. That tooth hangs out through the window of the barrel. Find the ridge on the barrel and on the bucking and mesh that up so you can put that bucking around the barrel. Give it tiny little turns to get it on. While doing that be aware of not giving it too much turn because that way you loose your alignment. Keep the alignment and that way it’s not going to rotate anymore. At least it shouldn’t 😉

When put it on the barrel you will feel a little resistance when it’s almost in place. That is because of that one tooth on the inside top of the bucking that is hitting the end of the barrel. You have to push that over it so it will sits in the window that is cut into the barrel. Done? Now your bucking is in place.

Second, less common problem, is that your bucking simply wears out. As you know it’s rubber made and so it’s not the most durable part or longest last. If you play regularly Airsoft you know that you have to replace it sometimes.

Hop-up adjustment

A properly adjusted hop-up will give you a longer range and better accuracy. Aside from a properly adjusted hop-up, the most effective methods for increasing your range are adding a tight bore barrel, hop-up nub and bucking. It’s also helps to regularly polish and clean your inner barrel.

So if you want to play with an Airsoft replica without doing these upgrades by yourself then I highly recommend the Elite Force CQC Airsoft replica.  This Airsoft replica has these upgrades directly from the factory and it has got some range tools. You may not believe me but this replica is actually better then many long range rifles.

Now let’s move on to adjusting the hop-up. It depends on your Airsoft replica how easy it is to adjust your hop-up.

Airsoft replica hop up

The M4 style Airsoft replica has a simple valve that covers the hop-up adjusting wheel. You can open it from the outside. The green dial you see on the left image above is the hop-up adjustment tool. Turn this dial counterclockwise until it stops. You should have no hop-up now and the BB’s have no backspin anymore.

If you want more hop, turn the dial small increments to optimize your hop. Keep adjusting the dial small increments until the BB’s have a very flat or straight flight pattern with a little upward move on the end.

The AK style hop is just a bit different but works the same. Most AK’s have a slide bar hop-up adjustment. Slide the  bar towards the barrel for no hop and move the slider towards the receiver for full hop. Keep adjusting until you get a straight flight pattern.

Lastly the G36 style hop-up. This style Airsoft replica has a drum style hop-up adjustment. Take a pin and turn the wheel up for more hop-up and turn it down for less hop-up.

When to make hop-up adjustments?

It’s nice to know how to adjust your hop-up but when do you have to make hop-up adjustments? Well, that kind depends on how often you play, your gear and how you shoot.

You will need to make hop-up adjustments:

  • Each time you change the weight of your BB’s
  • When you change between BB brands
  • After long time intensive play

If you change your BB weight the flight trajectory of your BB’s will change. A heavier BB weight does not necessarily mean that you have to give it more hop. The acceleration due to gravity is exactly the same whatever the mass. Heavier BB’s will hit the ground at the same time as lighter BB’s, but will have traveled a shorter distance because the FPS that is given through the BB is lower.

Somehow there’s a difference between the same weight of BB and a difference in brand. So if you plan to change the brand of BB you’re using, keep in mind that you probably have to adjust your hop-up. So do a bit of research first before you change the brand. Lately I wrote a big article about BB’s. Follow this link to that article. 

After a long time of intensive play it will happen that the adjustment wheel can slowly begin to move itself due to vibration. To avoid this as much as possible, check if the screw from the adjustment wheel is screwed tight enough when you maintain your Airsoft replica. Don’t screw it too tight because it will be harder to adjust.

Hop up adjustment of a GBB pistol

Most of the GBB Airsoft pistols have the same type of hop-up unit inside. For example the Tokyo Marui, KWA and WE pistols. You have to slight back the slide until it reaches that extreme point. Use a pen or something equal and push out a pin. Now you’re able to remove the upper receiver sliding it forward.

On the upper receiver you will find a little dial in front of the spring. On this dial you find an arrow which indicates which way to hop up.

Once you adjust it where you wanted it, slight the slider back on, push it all the way backwards and push the pin back. You’re up to go now!

Other pistols like the the KWA are delivered with a special tool to adjust your hop-up. Slide back the slider a bit until it exposing the inner barrel. You will see a teeth inside which you can adjust with a wrench. Adjust it clockwise to give less hop up, counterclockwise to give it more hop. Pretty straightforward and really easy to do!

Airsoft hop up bucking types

If you are planning to change your hop-up bucking be aware of the different types of hop-up buckings on the market. There are hard types and soft types of bucking.

A hard type hop-up bucking is made for higher FPS AEG’s such as the JG. This replica tends to shoot a little bit harder than other AEG’s. An advantage of a hard hop-up bucking is that they are going to last longer in a higher FPS set up. A disadvantage is that they tend to be less consistent with your shots and lead to less accuracy.

Soft type hop-up bucking are made for lower FPS replica’s. This is because the softer material is more likely to tear under hard usage. It is possible to use them in high FPS replica’s as long as you change them out occasionally and keep them well maintained. With these soft hop-up bucking you are able to get a better consistency as far as accuracy goes.

Airsoft hop up upgrades

If you want to upgrade your Airsoft replica, I would definitely choose for an R-hop-up. This is a relative new invention and is one of the best upgrade you can do on your replica.

The R-hop-up

What is actually an R-hop-up? The R-hop is the best accuracy upgrade you can have in Airsoft. It replaces your traditional hopup mound with an extended contact patch(1). When I did my research on the internet It felt like the best invention since the light. The R-hop can improve many factors like range, accuracy, backspin and use of heavy BB’s.

R-hop-upLike a regular hop-up, it the R-hop-up has a rubber surface that goes through the cut-out window of the inner barrel. The way it differs from a regular hop is that it completely matches the profile of the barrel.

How does it works? With a regular hopup, the BB has one single contact point with the bucking. That is the tooth inside the bucking that hangs out the window that is cut into barrel. With an R-hop-up the BB has not one single contact but the BB makes contact along the entire width of R-hop patch.

The R-hop is completely adjustable and they can work with any ammo weight.

Can you just install the R-hop by yourself? Well, that’s a tricky point. Compared with other hop-up systems, the R-hop-up system needs to be tailored to each individual set up a lot more. You also have to think about the hardness of rubber you’re going to use and the length of the patch.

So installing the R-hop may require an expert as many things can go wrong and a lot of factors (more than with the regular hop-up) has an impact on the performance of the R-hop.


The hop-up systems is one of the most essential parts of your Airsoft replica. It will contribute to your accuracy, range and consistency. However, how you’re going to perform depends on several factors like the shooter (you!) , the inner barrel, gearbox and hop-up system. But the hop-up systems plays one of the biggest roles in accuracy and range.

A whole new invention is the R-hop. A perfectly installed R-hop system has an advantage on many factors like range, accuracy, use of heavier BB’s, durability and backspin. However, the installation requires a lot of work. It needs to be tailored to each individual set up. To make R-hop patches seems to be the most difficult part.

(1) www.hopsystem.com
(2) Wikipedia image