top of page

What's Inside SPLATRBALL Gel Blaster?! I Take Apart SRB400 Gel Ball Blaster To Upgrade It

Watch the full teardown video:

Watch the Full Gearbox Take Apart and Put Back Together Video:

Watch the Metal Gear Upgrade + Stronger Spring Video - Part 1:

Watch the Metal Gear Upgrade + Stronger Spring Video - Part 2:

Splatter Ball blaster is the most commonly available blaster sold in the US. It can be found at many Walmart stores, sporting goods, and online. It is sold by Daisy.

CAUTION! - Splatrball and other Gel Blasters should be treated as weapons and should not be used in public or areas where someone who is not part of the game can be hit. The police will charge you with assault with a weapon. There have been multiple instances in the news of people (mainly teens) being charged with crimes for shooting unsuspecting people in public. The gel ball projectiles can cause permanent injury to unprotected eyes and face.


The "safety" glasses that come with most gel blasters are junk. The Splatrball glasses are better than most, but even with multiple adjustments, they don't fit well on everyones face, and can leave areas exposed. Gel balls can smash around the perimeter of the glasses and gel ball shrapnel can get in the eyes. Safety goggles will provide better protection than glasses, and may confirm better to different face shapes.

Revision Locust military goggles are recommended by many airsofters as the best eye protection. These goggles are used by the military and have higher impact ratings than standard safety glasses and googles. They also have better anti-fog and ventilation. If you find that they fog up, the foam can be removed from the ventilation holes to allow better airflow. The foam is there to reduce dust and particles from entering. The Revision Locust goggles can be purchased online, or in military surplus stores.

FPS (Velocity)

The Splat-R-Ball blaster is advertised to shoot at 200 FPS (feet per second). Testing with a chrono indicates that it shoots at an average of 210-220 fps. 200 fps is the minimum. So their claims are underrated which is good, and uncommon.

Reaching 300 FPS for a blaster like this would be amazing. 350 FPS would be the max at which you start to get diminishing returns of accuracy and increased gearbox wear.

If you want to increase the FPS so that the gel balls go faster, further, and hit harder, then there are several modifications to be made.

The first thing to inspect is the piston seal. Stock o-rings often do a poor job sealing the piston. Check the compression of the cylinder and see if it is strong. Replace the o-ring with a flourine o-ring for better seal. This will increase the FPS.

Check for air leaks. Any air leaks will drop the FPS.

Increasing the spring force by changing the spring will increase the FPS. However the stock spring is optimized for safety (higher FPS can cause more injury), and reliability. Increasing the spring force will lead to premature failure of the plastic gears in the gearbox.

RPS (Rounds Per Second)

To be honest, I think it's silly to chase a higher fire rate. The 7+ rounds per second these blasters shoot at is already crazy and makes game play less fun if you're just trying to hide from a rain of gel balls.

Higher fire rates are achieved by either increasing the battery voltage, changing the gear ratio, or increasing motor speed.

You can not simply use a higher voltage 3S Lipo battery without consequences. It may work for a while, but it will decrease the lifespan of the gearbox and strip the gears sooner than later. In order to reliably use a 3S 11.1V Lipo, you will need to change to metal gears and a piston with a metal rack.

Changing the gear ratio requires upgrading to metal gears and may stress the gearbox and require a higher torque motor, which needs larger diameter wires to carry more current.

A higher speed motor will have similar effects to a higher voltage battery. It will also decrease the life of the gearbox and will consume more current.


The stock battery is 7.4V lion cylindrical 18650 2 cell pack. It may be tempting to try to use a 11.1V 3S battery to increase the rate of fire, but doing so will drastically decrease the lifespan of your plastic gear gearbox.

In order to reliably use a 3S 11.1V Lipo, you will need to change to metal gears and a piston with a metal rack.


Watch this video on how to take apart and put back together your Splatrball gearbox. The same gearbox is used in the SRB400 and SRB1200. The SRB1200 is missing the single fire cam follower lever.

NOTE: The gearbox uses a slightly larger piston plunger than the airsoft standard. This means that a standard airsoft piston plunger will not work, come off the track and jam the gears, unless modified. See the PISTON section below. Because of this, it will be easier to replace the whole gearbox. The WELLS G36c gearbox is reported to have the exact same issue when attempting to upgrade the piston plunger body. They did not manufacture it to the industry standard.

The Splatrball gun gel blaster is based on the popular Wells G36c blaster which uses what is known as a V3 gearbox. V3 gearboxes are not commonly used in gel blasters, but are extremely common in airsoft. Most airsoft gearboxes are either V2 or V3. The main differences between an airsoft gearbox and gel blaster gearbox are the cylinder head, and plunger are sized differently for the larger gel balls, and the tappet stroke length (travel distance) is greater, and the tappet cam shape is different. Slight modifications may need to be made to the gearbox, since the cylinder head length is longer and the tappet will have to travel further back. The wall on the tappet slot where the tappet contacts when retracted may need to be cut back to allow the tappet to travel further.

You can replace the gearbox as a whole unit, but the cost could be almost as much as the blaster itself. Currently, the only place to buy a gel blaster V3 gearbox is from Asia, like Zhendou or Alibaba, but they are out of stock. The [not recommended] cheapest full airsoft v3 gearbox I have found costs about $29, but you will need to reuse your cylinder head and plunger, or buy a new gel blaster compatible cylinder head and plunger. The piston-cylinder will probably need to be reused, or the new one properly ported. I purchased one to try, but don't recommend this gearbox because it's plastic copy of metal airsoft gearboxes and wasn't designed with proper reinforcement to be made from plastic, especially around the trigger area, the gearbox has way too much flex, and the trigger pivot pins can pop out of place. Also, there's no quick-change spring access, so the whole gearbox shell must be disassembled change the spring. In fact, most V3 gearboxes don't have quick-change spring access, so it's difficult to find one that does.

[UNTESTED] This is an all-metal airsoft gearbox that has quick-change spring access [Motor and cage not included]: APS "Silver Edge" 8mm Version 3 Airsoft AEG Gearbox

The above gearbox appears to be of decent quality, but APS has a poor reputation (at least online) on the airsoft community for quality. Maybe if you don't push it, it will be ok. Slight modifications will need to be made as discussed above to make everything work for gel balls.

[UNTESTED] Here's the gel blaster version of the APS "Silver Edge" that is a drop-in replacement. (Rear Wired) V3 Complete Gearbox For Real Wood AK74

[UNTESTED] This V3 gearbox is sold as a gel blaster replacement and can be ordered from Zhenduo: JM Jinming Gen11 Gen12 J11 J12 AK Gearbox

[UNTESTED] Retro Arms has an excellent reputation for quality. They make a CNC 7071 Aluminum gearbox V3 that has a quick-change spring access. It's just a shell, and you have to add all the parts. May require slight modifications (like cutting back the tappet plate slide wall).

[UNTESTED] Plastic (Airsoft) Gearbox most similar to the original [not recommended, see why above]: Double-Eagle-Airsoft-Plastic-Gearbox-for-AUG-or-JG0448-AEGs-62450

[UNTESTED] Metal Gearbox Shell CNC Machined Aluminum [not recommended, No quick-change spring access, expensive, shell only]: Lancer-Tactical-CNC-Machined-Version-3-Gearbox-Shell-for-AK-AEGs-Red-65675/

[UNTESTED] Large selection of gearboxes, shells, both metal and plastic: EVIKE V3 Gearboxes


The Splatrball uses a 480 size motor, which is a quite strong motor. This is the same motor used for airsoft V3 gearboxes, and it is upgradeable.


The gears in the Splat-r-ball gearbox are made from Nylon. They are the same size gears for airsoft or gel blasters. The piston and attached gear rack are also the same. V2 or V3 airsoft gears and piston are compatible. Replacement nylon gears must be purchased from Asia, as it is very difficult to find non-metal airsoft gears in the US. The thought is that if you're going to take the time to replace the gears, it's either because the plastic ones have stripped or you want stronger gears, and in both cases, you would be changing to metal gears. Only buy quality CNC machined metal gears. Cast metal gears will not last.

There are many ratio options available for the gears. The default is 18:1. A ratio like 12:1 will give you a faster firing rate without using a higher voltage battery but will put more strain on the motor and gears.

Zhenduo says that both V2 and V3 gears will work with G36c (of which Splatrball is a clone).

Plastic Gears

Here are some plastic gears for direct replacement if you want to keep it stock, but if you stripped your plastic gears, these will probably also strip eventually, so might as well upgrade to metal gears.

Metal Gears

It may be tempting to buy inexpensive metal gears, but expect to pay at least $20 for quality metal gears. The cheaper metal gears are sintered and will not last. Quality metal gears are CNC machined for better strength and wear resistance.

Metal gears are available in many different ratios. The Splatrball SRB400 uses 18:1 gears by default.

Where to buy metal gears:

[TESTED GOOD] These Rocket Airsoft CNC gears are rebranded SHS gears. SHS gears are highly recommended by airsofters as quality gears. Rocket Airsoft CNC Steel Gear Set for Tokyo Marui Spec Airsoft AEG Gearboxes (Type: 18:1 Standard)

[UNTESTED] These are metal gears sold for gel blasters by Zhenduo. The manufacture is marked as SHS, but it is known that there are a lot of SHS counterfeit gears of poor quality. Hopefully Zhenduo is reputable enough to sell the actual SHS brand gears. They are available in 3 gear ratios 18:1 16:1 and 13:1.

Sector Delay Chip

The stock gears have a modified tappet cam. The metal gears will have a pin style tappet cam. A sector delay chip will need to be added to the metal gears that imitates the plastic design to allow for proper feeding of the gel balls. Without the sector delay chip mod, you will have problems feeding gel balls into the barrel.

DIY Sector Delay Chip

[TESTED GOOD] I 3D printed a sector delay chip that is an exact copy of the original cam feature on the plastic gears.

Where to buy Sector Delay Chips

[UNTESTED] This sector delay chip may be the best option to buy because it goes completely around the metal pin. The original plastic cam feature is 0.5mm further away from the gear axis than the metal pin. 5KU Copper Sector Delay Clip ID: 61544 (Part-5KU-61)

[UNTESTED] Plastic sector del ay chips. May or may not work. Can easily be trimmed to adjust. Matrix SHS Airsoft Long Duration AEG Sector Gear Delay / Chip for Standard Gearboxes

Motor Pinion Gears

The gear sets do not come with motor pinion gears, because there are 2 types of motor shafts and so you must choose the correct motor pinion gear to fit your motor shaft. There is an O style shaft (cylindrical without flat), and a D style shaft (has a flat area on the shaft).

The Splatrball SRB400 stock motor has a D type shaft.

Where to buy Splatrball motor compatible pinion gear:

If you are replacing the motor with a different motor, take note of whether it is a D type or O type.


You're going to need to use some shims on the gear shafts to adjust the gears so that there is minimal play in the gearbox.

Anti-Reverse Latch

Once you replace all your gears with metal gears, you will also need to replace the anti-reverse latch with a metal one. It is not included with the gear sets. This is where the anti-reverse latch is located in the SRB400 gearbox.

The stock Splatrball gearboxes use a slightly different anti-reverse latch than is common with airsoft. The Splatrball anti-reverse latch has a straight shaft with a narrow latch, and the latch is free to slide on the shaft. Airsoft latches have a bushing on the shaft, which usually can not be removed. An airsoft latch can be used if you modify the Splatrball gearbox by cutting down the post that holds the latch.

Where to buy anti-reverse latch:


NOTE: The piston plunger inside the Splatrball SRB400 is slightly wider (than standard airsoft gearbox) where it meets the track in the gearbox. The distance between the gearbox tracks is also wider. The difference is less than 1mm, but it means that a standard airsoft piston plunger will get pushed off the track and jam the gears. It can be modded to work. Adding a ~1mm sheet of plastic to the top half of the piston plunger helps support it and keep it centered and on the track. Watch this part of the video (Starts at 10:48) to see the issue and how to fix it:

The piston inside the Splatrball is almost the same as used in V2/V3 airsoft pistons. Unfortunately, it is slightly wider than the standard, which means that finding a replacement is difficult. Airsofters recommend a plastic (Nylon, Delrin, or Pom) piston body with metal gear rack. They say that the body benefits from the flexibility and lightweight of plastic, but the gear rack teeth need to be hard to stand up to the metal gears.

Pistons come with different numbers of teeth on the rack. The standard is called 15 teeth, but is actually 16 if you count the pickup tooth as the first. The problem is that the sector gear may want to grab the piston from the second gear instead of the pickup gear. Therefore, many people mod the standard 15 teeth gear racks by removing the second tooth (the SHS 15 tooth I did not require removal of the second tooth. It was already ground down far enough to clear), usually by grinding it down with a dremel tool. If you buy a 14 tooth piston, the second tooth is already removed so you don't need to do it yourself. It seems that 14 tooth pistons are the most popular to upgrade to.

SHS blue plastic body with metal gear rack pistons are highly recommended for airsoft, so should be perfect for gel blaster upgrade.

ID: 62386 (PT-SHS-TT0093)

[SPACER NECESSARY TO FIT SPLATRBALL GEARBOX - UNTESTED] Tube that should work as piston plunger shim (untested but dimensions and material seem similar to what I used) Wear-Resistant Nylon Tube, 1/32" Wall Thickness, 7/8" OD, 13/16" ID, 5 Feet Long -

Zhenduo says that both V2 and V3 piston will work.


NOTE! The piston head on the Splatrball SRB400 does not follow the standard O-ring slot size that airsoft or other gel blasters use. It uses a narrower slot and airsoft/gel blaster o-rings will not work. Watch this part of the gearbox video to learn more about the stock SRB400 piston head.

The piston and piston head are sold separately.

[TESTED GOOD] This piston head (MATRIX is SHS brand) is recommended by airsofters. Matrix Silent Piston Head for Airsoft AEGs Model #: PH-PT001

O-RING (Piston)

NOTE! The piston head on the Splatrball SRB400 does not follow the standard O-ring slot size that airsoft or other gel blasters use. It uses a narrower slot and airsoft/gel blaster o-rings will not work.

All of the following o-rings do not work with the stock piston head. You will need to replace the piston head.

These are the "official" green o-rings that are recommended to improve the piston seal and gel blaster performance.

Members on the Gel Blaster forum recommend this size and material of O-Ring to be used in basically all blasters.

20.2mm ID x 2.4mm x 25mm OD - Flourine Rubber

[TESTED GOOD] McMaster only has VITON brand o rings. Viton is a fluoro elastomer, and therefore probably the same or similar to the "flourine rubber" o-rings.


The tappet is the long piece that goes between the drive gear and the plunger.

Here are some airsoft tappets that should be compatible, but may require minor tweaking or a sector chip add on to adjust the travel distance.

Cylinder Head

Gel Blasters require a different cylinder head than airsoft. The length of the space for the tappet plate and nozzle to slide is longer than what is required for airsoft, due to the use of larger gel balls.

If you are replacing the whole plastic SRB400 gearbox with a metal gearbox, you will need to reuse the cylinder head from the SRB400.

Air Nozzle

The air nozzle on the SRB400 measures about 42.5mm in length (metal part only, the rubber tip extends a little further), and 8.3mm in diameter. This is larger than airsoft nozzles that step down.

It does not have any o rings on the inside, which would really help with air leakage and improve FPS

Gearbox Springs

If you lose any of the small springs, don't fret, there are spring packs available to buy for cheap. [UNTESTED] Make sure that you choose the Version 3 Gearbox spring set. or this set.


It's important to keep the gears, piston, seals and o-rings well lubricated. Since you are shooting gel balls that are likely to be wet, the water can speed up the washing away of the lubrication.

This lubricant is recommended by members on the gel blaster forum for lubrication of the gears, o rings, and seals. [TESTED GOOD] Super Lube 21030 Synthetic Grease (NLGI 2), 3 oz Tube


The trigger contacts are prone to failure due to the high current, especially when using a stronger motor or 11.1V battery. A MOSFET is a common upgrade for airsoft to eliminate wear of the trigger contacts. All the motor power is passed through the MOSFET, and the trigger contacts control the MOSFET.

[UNTESTED] This is a drop-in MOSFET for a V3 gearbox made by JeffTron. also available in the US here or here.

[UNTESTED] This MOSFET with active braking can be used with any blaster: JAG Arms Active Braking MOSFET with Wiring


Replacing the spring without upgrading the gearbox housing and gears is guaranteed to destroy the gears or something else. If the stock spring is still firing too slow for you, then after you upgrade to metal gears, then you can upgrade to a stronger spring.


How To UPGRADE 800 Round SplatRBall Drum Mag to 1200 Round and use it on the Splat-R-Ball SRB400 Gel Blaster Gun

What's inside a SPLATRBALL SRB400 mag?


Hardened Gel Balls

Hardened gel balls perform so much better than the soft stuff that comes with the gel blasters.

I use the WARINTEREST 3.0 RED HARDENED GEL BAL and they feed and shoot perfectly. They shoot more consistently, precisely, and never burst in or coming out of the blaster.

Glow In The Dark Tracer Gel Balls

Before you can even consider glow in the dark tracer balls, you will need a way of lighting them up. Take a look at my tutorial video on how to make a very cheap tracer light built into the blaster and powered off the blaster battery.

So far I've only tried these GELSTRIKE glow in the dark balls. They glow well. They are about the same hardness as the generic gel balls. Not nearly as hard as hardened gel balls.

Standard hardness glow gel balls can be bought in bulk (1kg ~ 200,000+) for relatively inexpensive: Zhenduo Toy ZHENDUO 7-8mm 1kg Glowing Gel Balls

I've only seen hardened glow in the dark gel balls available to order from Asia, and they are kinda expensive.

Glow In The Dark Tracer Mod

In order to use glow in the dark tracer balls, you will need a way to light them up before they leave the blaster. There are expensive tracer units that attach to the end of the barrel, but these are expensive and add complexity (another battery to charge). I modded the blaster with a single UV LED inside the t piece that lights up the glow gel balls right before they are shot out. The LED is powered off the blaster battery and only lights up when the trigger is pulled. It's simple and works great.

Watch the tracer mod video:

How to mod the Splatrball SRB400 mag into a tracer mag:

Splat-R-Ball SRB1200 Tracer Mod Video. The SRB1200 is so easy to add a tracer mod because there are already LEDs inside and an LED driver board. No parts or soldering are necessary. All you need is a drill, drill bit, and gel super glue.


WARNING! Modding the appearance of the exterior may make this blaster look even more realistic and is not recommended. As Splat-R-Ball themselves recommend, do not brandish this blaster in public or anywhere that it could be confused for a real gun.


Watch how to add this aftermarket rail (unfortunately it is not picatinny compatible):

This picatinny rail and quick release could be added on top of the Splatrball SRB400.

This rail was designed to fit on a G36c, but it won't be a direct fit onto the SRB400 and will require some modification


▶ Products we make:

▶▶ Amazon Store:

▶ Engineering:


▶ Instagram:

▶ Facebook:

The products shown here were purchased by me with the intent to use them. I did not receive any free items, and I am not being paid or compensated for this review. The video, description, and comments may contain affiliate links. If you click on a link, I may receive a commission. Money earned helps to support my channel and bring you more informative videos about engineering, crafting, and DIY.


Recent Posts
Search By Tags
Follow Us
  • Facebook Basic Square
  • Twitter Basic Square
  • Google+ Basic Square
bottom of page