Simply Airsoft Guns

Introduction

When I started upgrading airsoft guns I had no previous experience in upgrading and gearbox maintenance but with a little help from Youtube, Mechbox and other sites I successfully took the gearbox apart, extended the barrel, changed the motor, changed the spring, re-shimmed the gearbox, replaced the bushings, greased the gears and put it back together again.

The only way to learn how to upgrade your guns is to give it a go, and it’s really not as difficult as some people may have you believe. However, it does require thought and patience, so make sure you are fully informed before you begin any maintenace.

I have tried to make the upgrade guides as clear as possible; if you fancy upgrading your airsoft lectric guns and are confident that you can do it then I recommend giving it a go – after all, you won’t learn until you try. As with any project of this nature, if you haven’t done it before, make sure you keep track of all the parts and their placements as you remove them. The best way to do this is by taking pictures as you go along.

If you have any doubts, try it on an old gearbox first, seek the help of someone more experienced, or have the upgrades performed by a professional.

Before you start

Make sure you read all these instruction fully before you begin taking your automatic airsoft guns apart. The parts you choose to upgrade with are entirely your responsibility. Do not upgrade one part of your aeg airsoft guns without considering the wear and tear on the rest of it. For example, higher powered springs require reinforced gear sets and higher torque motors to maintain rate of fire. Make sure you have taken these into consideration before you begin any maintenance.

Changing and/or extending the barrel

Gun barrels can be easily interchanged to use a tightbore (a thinner barrel that improves accuracy) and/or lengthened to increase effective range. With the silencer added, the A&K SR25 can fit a 650mm barrel – so let’s crack it open!

Note: I’ll be taking down your airsoft bb guns with the barrel to the right and fire selector switch face down.

Like many M4/M16′s, the SR25 quickly takes down in two halves, splitting at the upper and lower receiver. Unscrew the two alan key heads near the fire selector and the front of the magazine receiver (highlighted below), and push the holding bolts through.

Note: Be careful when removing the front holding bolt – the upper receiver will spring outwards.

Figure 1: Unscrew the two heads of the two holding bolts around the receiver.

Figure 2: The location of the two holding bolts

The removal of the holding bolts will release the upper receiver, the inner barrel and the hop-up unit.

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What’s a hop-up unit?

Hop-up units are ‘T’ shaped plastic or metal compartment that fixes onto the end of the barrel and sits above your bb airsoft guns magazine (see figure 3 below). The unit contains a hop-up, a cylindrical piece of rubber that presses on the bb’s as they enter the barrel adding spin, straightening bb flight and extending the guns effective range.

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Wiggle the charging handle (the ‘T’ shaped piece of metal used to cock the rifle) over the ridges on the gearbox and separate the two parts.

Grab the upper receiver half and pull the hop-up unit and barrel out of the front end slowly, making sure the barrel is completely straight as you remove it.

Remove the clip from bottom of the hop-up and slowly pull the barrel out, making sure it is not twisting as you go. Be careful as you handle the hop-up unit as it contains the hop-up rubber – a very small rubber piece that can fall out easily.

On the barrel you’ll see a retaining clip and a (roughly) 2cm long piece of rubber, known as the hop-up bucking (see figures 3 and 4 below). Remove both of these.

Note: The hop-up bucking may have remained in the hop-up unit as you removed the barrel. If so, remove it from the unit.

Figure 3: The hop-up unit.

Figure 4: The barrel and hop-up bucking.

Have a look inside the hop-up bucking; you’ll notice a thin rubber ridge, which acts as a guide for placing it on the barrel. Now have a look at your new barrel. You’ll see a groove cut along one end (see figure 5 below). Line up the hop-up bucking ridge with the groove on your new barrel and push it on.

Figure 5: Hop-up unit placing on barrel and groove guide for hop-up bucking.

Changing the hop-up rubber

Before we put the barrel back in the hop-up unit let’s change the hop-up rubber. (Generally) soft hop up rubbers are more effective by tend to wear out faster, and vice versa for harder rubbers. Which is best is hotly debated, so for more advice on which one to use, visit one of the many airsoft electric guns forums online.

Assuming the tiny hop-up rubber has not already fallen out, grab the hop-up unit and lightly tap it on a table. The hop-up rubber should fall out.

Pick up the hop-up unit and turn it with the cogs facing downwards. Have a through the central cavity. You’ll notice a cavity inside the unit, which is where the hop-up rubber will sit.

Figure 6: Hop-up rubber cavity inside the hop-up unit.

Carefully roll your hop-up rubber down the cavity until it sits flat in the cavity. Now turn the hop-up adjustment wheel. The hop-up will raise/lower as you turn the wheel, adjusting the amount of ‘hop’ the bb’s will receive.

Now lower the hop-up all the way down so that it sits as far into the cavity as possible. Place the hop-up unit back on the table being careful not to dislodge the rubber.

Putting it back together

Now it’s time to put your airsoft guns back together. Push the barrel with hop-up bucking back into the hop-up unit as per figure 5 above, i.e. with the hop-up unit pointing down and the groove on the barrel facing towards you. It may take a little wiggling to get the barrel in.

The barrel will have two grooves on either side that line up with the retaining clip. Keep pushing the barrel in until these line up with the space for the retaining clip. Now push on the retaining clip until it clicks.

With the barrel in the hop-up unit, look through the unit and ensure the hop-up rubber raises/lowers as you turn the hop-up adjustment wheel.

Assuming all is working, slowly slide the barrel and hop-up unit barrel first back into the front end of your gun. Align the front half back on top of the back half the same way as you took them apart – slide the front half on above the gearbox, wiggling the charging handle over the ridges on the gearbox. Once in place, push the holding bolts through and screw the alan key tops on.

Note: You may find the ejection port prevents the front end from sliding on. The easiest way to prevent this is to replace the flap and turn the receiver face down to keep it in place as you slide the front end on.

Once together, put on your safety goggles, load a magazine and test it. Make sure the bb’s fire out the gun and fly straight as you apply more hop-up. If one of these is not happening, take apart the gun and repeat the above, ensuring the hop-up rubber sits flat in the unit and the hop-up bucking and barrel and placed at the right orientation into the unit (see figure 5).

That’s it!

Congratulations, you’ve now learnt how to change your hop-up rubber and change / upgraded your barrel!

Now you’ve got an upgraded weapon, why not film your success? Read about the Oregon ATC2K ActionCam by clicking airsoft guns.   To return to the homepage, click Simply airsoft guns.