Electric Gel Blaster Pistol Troubleshooting Guide

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In the second half of 2023 to the present, many brands have suddenly started to launch various models of gel blaster electric pistols. Hayabusa and BQ are the true pioneers. To this day, all the electric pistols on the market are derivatives of these two systems (FDC’s system is based on Hayabusa's, DS and UDL copied FDC, and TP9 copied BQP99).

The design of electric pistols requires integrating the gearbox into a very small space, with many parts requiring structural space tolerance to be within fractions of a millimeter. In some special positions, the interference of a strand of hair can cause the system to run poorly. This is not friendly for new players. Below, I will share my experience using the BQ series electric pistols over the past few years. I will introduce the structure of the BQ series electric pistols, explain the logic of the system, and provide some common problem analysis and solutions, hoping to give new players some helpful experiences.


The Structure of the Launcher

1.Composition of the Electric Pistol Launcher

Upper assembly: consists of the slide, front sight, rear sight, outer barrel, inner barrel, chamber, return spring (including return rod), cylinder, piston, sector gear, and main spring;

Lower assembly: consists of the frame (including retaining pins), gearbox, and magazine (including battery);

The composition of the frame includes: frame main body, slide release group (including spring or selector), and magazine catch;

The composition of the gearbox includes: gearbox shell, trigger assembly (including trigger pins and trigger spring), empty hook rod (including fixed pin), trigger linkage (including linkage spring), magnetic (or selector) micro-switch, counter micro-switch, gear set (including bevel gear, large gear, sector gear, and bearings), latch (including latch spring), end cap, motor, fire control, and wiring group.

2.Operation Logic of the Electric Pistol Launcher

The operating process of the BQ series electric pistol is as follows:

  • Initially, manually pull the slide back to load the chamber, with the cylinder pushing the piston back until the piston's latch piece hooks onto the latch in the gearbox. At this point, the piston compresses the main spring, ready to fire, indicating the loaded state;
  • Insert the battery magazine, release the empty hook, and under the push of the return spring, the slide returns to its position. The pusher under the cylinder pushes a gel ball from the magazine into the chamber and inner barrel. At this moment, the latch piece holds the latch, maintaining the compressed state of the main spring;
  • Pull the trigger, the trigger linkage pulls the latch, releasing the piston's latch piece. The piston moves forward inside the cylinder under the force of the main spring, creating air pressure that propels the gel ball out of the inner barrel;
  • When the piston reaches the end of its stroke, the magnetic piece triggers the magnetic micro-switch (if it's a selector micro-switch, it's triggered by the protruding shape at the bottom of the piston squeezing the selector). This starts the motor, turning the gears, and pulling the slide back. When the sector gear completes a rotation, the teardrop-shaped protrusion on the sector gear compresses the counter micro-switch, sending a brake signal to the fire control, stopping the gear rotation, thus completing a cycle and returning to the state in 1);
  • If the magazine runs out of gel balls, the push plate reaches the top position (since the magazine feeds three rows, the push plate reaches the top when there is actually one gel ball left in the magazine). At this time, the empty hook rod on the push plate will contact the empty hook piece, lifting the empty hook. When the slide moves forward, the empty hook notch will be caught by the empty hook piece, thus realizing the empty magazine catch function;
  • The above describes a complete cycle of the launcher's working process.

Upper Assembly FAQ & Problems

1.Unable to release the empty hook, forcibly pressing down the empty hook, the slide hits forward forcefully, releasing the chamber.

Problem cause: The chamber is not properly loaded, the empty hook is engaged, but the piston is not hooked onto the latch;

Solution: Pull back an additional 1mm, listen for a "click" sound, confirming that the piston is hooked onto the latch;

2.What is the size of the original piston O-ring?

The size of the original O-ring is 14.6 (inner diameter) * 1.8 (wire diameter). Many experienced players have verified that the optimal size is 14.8 * 1.8.

3.How to solve the issue of the slide being rough?

The issue of the slide being rough could be due to multiple reasons. It is advisable to use the elimination method to investigate one by one, first manually load the chamber, hook the piston onto the latch, and repeatedly pull the slide to observe the rough spots.

4.Slide unable to return to position by 1~2mm

Problem cause: The pusher is dry, unable to squeeze into the chamber during return;

Solution: Apply D70 lubricant to the pusher and both side rails (see below picture);

5.The slide moves smoothly after loading, but becomes rough and difficult to return after firing

Problem cause: After the main spring is compressed, it deforms, creating downward pressure, pressing the piston's ears onto the slide rails, creating friction during the forward push;

Solution: Pad the area under the end cap to ensure that the direction of the main spring deformation is as parallel to the end cap as possible (see below video);

6.The slide is not smooth to pull back and forth after loading

Problem cause: The slide interferes with components on the frame; observe the wear on the slide, then analyze the interference points; common rough spots include: the chamber's offset slope to the upper part of the slide; interference between the slide rail and slide release catch (see below picture); interference between the slide rail and the frame rail (third-party slides often have this issue, originals usually don't);

Solution: Polish the areas that are not smooth, where there is friction, there should be polishing.

7.How to match the original upper assembly screws that flew off?

Problem cause: The slide vibrates a lot, and it's a matter of time before the threaded structures become loose.


  • Tighten the screws regularly during maintenance;
  • Apply low-strength screw glue (not recommended, it will be troublesome when disassembling);
  • Keep a variety of screws on hand:
  • P99 & G17 front sight screw: m24;
  • P99 & G17 rear sight screw: m24;
  • VP9 front sight screw: m25;
  • VP9 rear sight screw: m26;
  • G17 MOS plate fixing screw: m2.56;
  • VP9 end cap screw: m1.744;
  • VP9 cover plate fixing screw: m2.56;
  • VP9 red dot screw: m310 (this length is compatible with RMR, different red dots may have different thicknesses, length needs to be adapted)
  • 99 & VP9 inner barrel fixing machine screw: m36;
  • G17 inner barrel fixing machine screw: m4*6;
  • Common Lower Assembly Problems

8.Empty hook failure

Problem cause: The empty hook rod of the magazine does not contact the empty hook piece, and does not lift the empty hook piece.

Common possibilities include:

  • Broken gel balls in the magazine press the push plate position;
  • The empty hook rod on the push plate is deformed, not reaching the empty hook piece;
  • The empty hook piece is deformed, pressed by the gearbox shell and frame, and cannot be easily lifted
  • Clean up the debris inside the magazine;
  • Remove the slide, insert an empty magazine, observe if the empty hook rod can contact the empty hook piece and if it can easily lift the empty hook piece. If not, deal with the deformation based on observation results;

9.Empty hook on every shot with gel balls present

Problem cause: The empty hook piece is abnormally lifted.

Two possibilities:

  • The trigger spring is installed incorrectly, the long side is not pressed under the crossbeam;
  • The gearbox shell is cracked, lifting the empty hook piece (TP9 and early VP9 had this issue, later VP9 changed the gearbox data, eliminating this problem);
  • Correctly install the trigger spring;
  • Insert a toothpick or wire into the gap between the gearbox shell and the frame, as shown below;

10.Trigger does not rebound after being pressed

Problem cause: The trigger or trigger linkage interferes with the gearbox or frame, getting stuck.

Common places include:

  • The trigger safety contacts the rear part of the trigger hole on the frame;
  • The trigger linkage is deformed;
  • The protrusion on the G17 trigger linkage contacts the upper slide;
  • Solution: Find the contact point, polish it by 0.1mm, if the trigger linkage is deformed, remove it and straighten it by applying slight force;
  • Common Overall Operation Problems

11.Semi-automatic failure turns into manual operation

Problem cause: The signal that triggers the gear rotation is ineffective.

Possible reasons include:

  • Wiring group connector falls off;
  • The battery contact is bent, not reaching the battery discharge plate;
  • Magnetic micro-switch is detached from solder;
  • Fire control & motor damage;
  • Battery damage;
  • Piston magnet falls off (selector micro-switch breaks off);


  • Follow the steps below to locate the problem, then address it specifically:
  • Remove the battery, measure the battery core voltage with a BB response, ensuring the battery is usable;
  • Remove the battery, observe from below whether the battery contact on the gearbox is bent. If so, straighten it (it's best to remove the circuit board and bend the contact to an obtuse angle to over-correct it);
  • Remove the slide, check if the piston magnet has fallen off. If so, you need to replace the piston or reattach the magnet;
  • If it's a selector micro-switch, check if the selector has been blown off or deformed. If so, you need to replace the selector micro-switch;
  • Disassemble the gearbox, insert the battery, use the piston to trigger the gearbox operation, observe whether the gears turn. If it can rotate each time, then the issue is not with the gearbox;
  • Check if the mini4pin wire socket on the back of the gearbox is loose, if so, plug it in tightly;
  • When the gearbox is powered and the piston is triggered, if the gears do not turn, press the debugging button on the back of the fire control. If the gears do not step turn, then it's likely that the fire control & motor are damaged, requiring factory maintenance or replacement by yourself;
  • If the debugging button works but the micro-switch cannot trigger the gears to rotate, then it's likely the micro-switch has detached from the solder. You need to disassemble the gearbox and resolder the micro-switch wires;

12.Slow creeping in continuous firing

Problem cause:

  • Insufficient discharge capacity, causing the gears to not pull the slide back quickly, and the slide is pushed back before the piston hooks onto the latch. This is especially likely to occur when lithium battery performance declines in winter;
  • The sector gear is not glued firmly and slips out of the cylinder slot;
  • Warm up the battery before playing;
  • Replace with a high-discharge expanded battery;
  • Re-glue the sector gear in place (recommended to use 5800 glue);

13.Rapid continuous full-auto fire

Problem cause: The piston fails to catch the latch, possible reasons:

  • The latch piece of the piston falls off or breaks;
  • The latch spring on the end cap breaks, unable to lift the latch (normal latch spring height as shown in the picture below);


  • Replace with a new piston;
  • Replace with a new latch spring, specification is m349;

14.The fired gel ball has no speed

Problem cause: Low initial speed, possible reasons:

  • The first magazine, the inner barrel is dry and not lubricated, with high resistance;
  • There are air seal problems;
  • Use several magazines to lubricate the inner barrel;
  • Address the air seal issue. First check the piston cylinder air seal, use an m14.8*1.8 O-ring, block the push nozzle and quickly push the piston. If there's significant resistance, this indicates a good air seal;
  • Then, address the inner barrel air seal as follows:
  • Install the chamber and return rod, do not install the outer barrel, then press and tighten the inner barrel from the top, tighten with machine screws to secure the inner barrel.


15.Incomplete rotation

Possible problem cause:

  • The battery is not plugged in tightly, power is lost mid-operation;
  • The battery is aged and severely lacks discharge;
  • Push the slide back (force can be applied, it can be pushed forward freely, but care must be taken when pushing back, as the sector gear may be pulled out), next time ensure the magazine catch is locked into place when inserting the battery;
  • Replace the battery;

16.Gear over-rotation issue

Possible cause:

  • The motor brush is aged;
  • The expanded battery discharges too powerfully;
  • Replace the motor;
  • For versions after April 2023, the fire control has an adjustment function. When using an expanded battery, adjust the setting to 1; when using the original battery, adjust to settings 2, 3 (see below video for adjustment method);
  • Replace with a brushless motor assembly;
  • Use a thicker spring to increase the gear load (not recommended, it will accelerate the wear and tear of the gearbox motor);

The above summarizes the thought process for addressing common issues. If you have other experiences to share, feel free to post them in the comments or send a private message to add to the article.

Electric pistols are currently the pinnacle of gel blaster technology. However, the structural characteristics of electric pistols determine that this is not a thing suitable for new players. Those who are familiar with the structural principles can play brilliantly, while those who are not tend to be at a loss over a small issue. Currently, all electric pistols on the market, to a greater or lesser extent, are derived from the structure of the BQ-designed electric pistols. Therefore, understanding the structure of the BQ electric pistols will help everyone better experience the joy of using electric pistols, instead of feeling like they spent thousands to buy trouble.

Finally, here's a happy highlight from our electric pistol game, hoping everyone can have fun!


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