MS-GnK: Dual Stage Brushless, Solenoid powered, Nerf Blaster, with a Milsim twist UPDATED V1.2

UPDATES:

19/09/2026

• Updates pushers, now slimmer to help them stop striking the dart lever. 

11/09/2026

• New Dart Guides, 2 options created, one with a dart detector switch, another without. Gives way more reliable readings compared to the IR sensor, and gives a better option for using manual solenoid timings. Archived IR sensor.

• Firmware updated for new dart sensor, no more detection calibration.

• Updated Cage Plate to have less thin walls.

• Updated Trigger and Mag Paddle to fit the 3mm shaft better.

28/07/2026

• New flywheel cage! This now consists of one printed part, and 2 metal plates to mount the motor. Plate .step file included, can be cut via JLCCNC or sendcutsend.

• Removed sub250 1304 motors as an option and replaced with RCINPower GTS V3 1404.6 motors, optimised for FDM printing.

• Reworked flywheels for RCINPower GTS V2 1207 motors, optimised for FDM printing.

• Added Non IR firmware so you do not need an IR sensor for the blaster to function.

• Reworked dart guide, IR PCB now slots in from the front, meaning it no longer sits loose.

• Adjusted tolerances for Top Plate and Button Release.

• Added alternative magwell

24/06/2026

• ESC Passthrough firmware added, eliminating the need for a flight controller to flash the ESC. Massive thanks to dpairsoft for compiling this. Build guide updated with instructions on how to use.

01/06/2026

• Updated tolerances on Upper Front, Rear, and Top Rail, alongside more space for the ESC.

• Thicker Cage Mount Front and adjusted PCARs, means barrel is less likely to wobble around and come loose

• Cage Roller geometry changed, pin also moved down to prevent it striking the flywheels

30/04/2026

• Made more room in Receiver Grip and Grip lid, can now fit 24x34x74mm size batteries (3s 1700mah, 4s 1300mah for example). Note that walls are quite thin (1.5mm) so may flex on assembly. Grip sleeve highly recommended.

20/04/2026

• Updated flywheel centre shaft holes to be tighter so they stay more central to the motor bell

07/04/2026

• Made more room in Receiver L for PCB as selector switch didnt sit all the way forward when soldered directly to pcb (if you don't feel like reprinting you can just wire the switch to the PCB via wires

23/03/2026

• Version 1.2 update! Now with custom PCBs, IR sensor, airsoft triggers, and build guide!

• PCB Gerber files added to fileset

• Updated hardware and electronics list

• Building guide added

• Firmware updated for IR sensor

• Wiring updated for PCBs and IR sensor

• Receivers updated to use PCBs and switch placement changed to take Airsoft M4 AEG airsoft triggers

• Removed Switch Plates

• Updated Pusher, now must use 10mm standoffs, thread size depends on your solenoid. Previous printed pusher has been removed

• Updated mag release to use less hardware and operate smoother

• Dart guide and Top Plate updated for use with IR sensor 

• Solenoid plate updated for use with PCBs 

• Selector switch updated for use with PCBs and less hardware

• Tolerances updated on Magwell and Top Rail

• Stock is now roomier, has an added sling point, and has the option to use Protean Printed Stock Bars

• Alu Flywheel Cages updated with grooved to make it simplier to fit motors

• Base trigger made beefier

07/10/2025

• Closed loop firing delay! Firmware now updated to utilise RPM feedback from the ESC to make sure the solenoid only fires when target RPM is hit. Adjustable values are included in the firmware.

• New stock created using Worker stock bars, able to fit a 4s 1500mah LiHv or a 6s 1100mah LiPo.

• Trigger grub screw hole removed, this caused a major weak point that has lead to some triggers snapping.

• Roller added to Cage Mount Front, this ensures darts feed smoother into the flywheels without entering too early. This is mounted with a 1.5mm Dowel pin

02/09/2025

• DShot update! Added new firmware that now utilises DShot protocol using bastian2001's DShot library, this enables much faster spinup time, cutting the solenoid delay almost in half! (Full Bidirectional DShot not used as of yet, you can read motor RPM but I haven't used that for closed loop control yet)

• Added Receiver Grip, this means you can use a battery in grip (only tested with 2x GNB 3s 1000mah airsoft lipos in series so far)

• Barrel modified to not wobble around as much, and also added a short barrel

• Pushers modified to be larger

11/08/2025

• Barrel retention method changed to a bayonet type fit, which is much friendlier on printing tolerances compared to a thread

• Added flywheel and flywheel cage for Brotherhobby VY 1504.5 2950kv motors, I have been running these to great effect on a 6s lipo (which is actually 2 airsoft 3s lipos in series)

19/07/2025

• Added locating nubs to Upper Front component, eliminating the need of filament pins to keep aligned 

• Trigger component made stronger, now less likely to snap in half

• Standoff pusher added, this uses a 6/32 6mm brass standoff that the pusher screws onto, then standoff threads onto the solenoid

• Magwell tolerances adjusted

23/05/2025

• V1.1 Update!

• Electronics changed, 3 position switches have been ditched in favour of a Rotary Potentiometer to adjust flywheel RPM, and a rotary selector switch to select fire mode.

• Firmware updated for new electronics.

• Tournament Lock added, this is a physical cover for the Potentiometer that can be tied off with a Zip Tie, physically shows that FPS cannot be adjusted without removal.

• Binary Fire added.

• Toolless Flywheel Access added, removed 2 bolts from the Upper Front assembly and replaced with a 4mm Clevis pin and M3 thumbscrew.

• Receiver halves adjusted for more space for new electronics, as well as ergonomic changes for some grips.

• Fast Decay circuit added.

• Additional M3 Grub Screw added to trigger for further adjustment of trigger throw.

• Cage Mount REAR adjusted with slot for cables to pass through

• STEP file updated and rearranged 

• .zip file for previous version archived

16/03/2025

• Chamfered the barrel of the PCARs to ensure the dart enters the pcar gradually, significantly reducing the change of a jam from a dart folding.

13/03/2025

• Pusher changed to shorten the solenoid throw, adding some precompression to the spring so it returns faster

• Dart Guide and Top Plate changed to accomodate more space for wires, Dart Guide can now fit a 35V 1000uf capacitor instead of a 25V capacitor.

06/02/2025

• Added new cage and flywheels supporting Sub250 1304 6000kv motors, as the RCINPower 1207 6000kv motors I originally used have been discontinued. Cage and wheels labelled to which motor they correspond to

• Machined wheel file removed, should be able to export the current flywheel models from the main .step if machining is needed

• Shortened the ESC mount to make mounting ESC much easier

• Created slightly more space for cables in the two receiver halves

• Removed 2x bolt holes for the top plate as they are no longer needed

• Rearranged .step file to make it easier to hide components you need to view without moving everything

12/01/2025

• Altered Cage Mount Front.stl to prevent darts catching if the dart is too far forwards in the mag, leading to a misfeed

02/01/2025

• Published

MS-GnK - Yet another GnK design

Another dual stage brushless flywheeler created by myself, the MS-GnK (Milsim GnK)

This dual stage brushless flywheeler boasts 26mm flywheels and a selection of different motors, hitting an average of 210fps with PCAR, as well as a select fire solenoid for semi, binary, and full auto fire modes, a “pre-rev” mode similar to the HC Diana, and adjustable motor RPM via a potentiometer. MS-GnK uses straight talons magazines and its derivitives, and functions best on Worker HE Darts (Tested on both standard and heavy weights). The Barrel is also able to take any kind of 19mm ID faux barrel, including Worker muzzles and various Tracer units. As of version 1.2, MS-GnK now included and IR sensor to detect darts in the magwell, allowing maximum Darts per Second.

MS-GnK uses a variety of Airsoft furniature, including an AEG stock mount, AEG and AR grip mounts, M4 AEG Triggers, and M-LOK mounting parts on the upper frame. These provide a lot of customisation option, just be aware that you will need a stock to fit the appropriate battery to power this blaster. 

I chronoed this blaster to approximately 210fps, this may be higher or lower depending on your build quality and motor setup, but I managed this through RCINPower 1207 6000kv motors on 3s/Brotherhobby Vy 1504.5 2950kv motors on 6s, and fresh 1g Worker HE darts. This was also using the included PCAR, which will drop FPS by about 5 or 10, but significantly improve accuracy. FPS can be changed by using the Rotary Potentiometer on top of the receiver. This may change dependent on your motor selection once again.

In V1.1 Update, a Tournament lock has been added, this is a physical cover over the Potentiometer that has a slot for a Zip Tie, making it visibly that FPS cannot be changed during play. 

There is a 6 land gonkin' PCAR modelled into the Flywheel Cage, which significantly improves accuracy. The Flywheel Cage is assembled with 2 metal plates that the motors sit on, significantly reducing vibration and helps with heat management. 

Firmware is included. As of 07/10/25, firmware uses DShot instead of servo/pwm to communicate with the ESC, this requires you to install bastian2001's bidirectional DShot library. This has enabled me to use the latest AM32 firmware without issue, and cut down the delay between revving and firing the blaster. Closed loop RPM feedback is also in this version, enabling you to decide the target RPM for the motors to hit that the solenoid should fire at. User defined values are included at the top of the sketch to adjust solenoid timings, firing delay (not in DShot version) motor KV, voltage, number of poles, etc. PLEASE adjust these according to what electronics you have included, otherwise it will not work properly. With correct tuning and settings, I have achieved a sub 100ms firing delay from pulling the trigger.

You are welcome to use your own firmware, different microcontroller, add a screen, whatever you like with this! I would love to see what others can do with this shell. I will admit this is not the prettest, but it works to get the blaster working at a minimum. You are welcome to use your own firmware, different microcontroller, add a screen, whatever you like with this! I would love to see what others can do with this shell. 

To Activate the Pre Rev mode, put the select fire switch in the Safety Position (Position 0 on selector switch), and pull the trigger all the way. You will hear a low hum from the flywheels as the spin at a low RPM. 

Within the firmware, there are settings to tune the solenoid timings, and set a threshold to when the solenoid fires. Full troubleshooting for this is in the build guide. 

The capacity of the LiPo depends on which stock you choose. The included stock can fit a GnB 4s 1500mah 120C LiHV and a GnB 6s 1100mah 60C lipo. I have tested this with an AEG buffer tube and GnB 3s 1500mah 30C Airsoft lipo, which stays in place with any kind of AEG buttstock, and I have also been using GnB 3s 1700mah 60C LiHV with a VFC QRS Sling Stock, which also fits inside the receiver grip.

This project is licensed under the terms of the Creative Commons Non-Commercial Attribution Share Alike 4.0 license, which means you can print it, remix it, share it, and if you do and give myself credit. You cannot sell this without permission from myself. 

**DISCLAIMER, THIS IS NOT AN EASY BUILD, REQUIRING TIGHT TOLERANCES AND VARYING MATERIALS, INCLUDING TPU PRINTS**

TPU prints include the flywheel cage mounting, which aims to reduce vibration. I also HIGHLY recommend getting the flywheel cage plates cut in Aluminium. There are many services that do this, such as JLCCNC and sendcutsend. Aluminium cage plates helps a lot with motor vibration and heat dissipation, which is essential considering the size of the motors and cage itself. I have included a .step file for the Alu Cage Plate model, alongside parts such as Machined Flywheels. These are also reflected in the main .step file. 

The option to use custom MS-GnK PCBs has now been added as well, this makes wiring a hell of a lot simpler and saves a lot of space. Files required to order your own PCBs have been added. I would recommend ordering through JLCPCB. Make sure you assemble bottom side for the Solenoid PCB. You do not need the PCBs to get the blaster working, there is the option to wire it up with bare components. 

Pinout/Wiring Diagram for Seeed XIAO rp2040:

• D0 -Dart Detection Switch

• D1 - Rev Switch

• D2 - Fire Switch

• A3 - Motor RPM Potentiometer

• D4 - Selector Switch 1

• D5 - Selector Switch 2

• D6 - Solenoid Mosfet

• D7 - D10 - ESC signal pins

With PCBs:

Without PCBs:

Note with powering the XIAO, there is also the 3.3V pin and the VIN pin on the underside on the board, you can use those instead powered at 3.3V or 3.7V. Please double check pinouts for the XIAO and ESC to make sure they match the pinouts in the diagram and firmware.

The 5KP30A TVS Diode pictured is for Fast Decay of the solenoid, enabling it to retract faster whilst still protecting the Mosfet. I have tested this setup on 6s Lipo voltages.

If you are not using the DartSwch firmware, you do not need to wire up the dart detection microswitch.

Hardware (Main):

• 9x M2x6mm Bolts (For Flywheel mounting and Selector switch)

• 16x M2x8mm Bolts (For Motor mounting)

• 16x M2 Washers (For Motor Mounting)

• 3x M2x12mm Bolts (For switchs)

• 11x M3x8mm Bolts

• 4x M3x12mm Bolts (For AEG Grip Mount)

• 1x M6x20mm Bolt (For AR Grip Mount)

• 10x M3 Nuts (4 required for AEG Grip, 1 for receiver grip)

• 1x M5 Nut (For AEG Stock mount)

• 1x M3 Thumbscrew

• 1x M4x16 Clevis Pin

• 1x 6-32/M4/M5 x 10mm standoff (For the Solenoid Pusher, thread depends on what solenoid you have)

• 16x M2 Washers (Optional but highly recommended for the motor mounting, saves the bolt drilling into the flywheel cage too far)

• 1x M3 Grub screw (Optional for the Trigger, means you can adjust the travel between the Rev and Trigger switches)

• Several 1.75mm Filament strands cut down for pins

• 1x small spring for Mag Release (I don't have measurements for these since I cut down assorted springs)

• 2x 1.5mm x 24mm steel dowel pin (For Cage Roller and Dart Lever)

• 2x 3mm x 14mm steel dowel pins (for Trigger and Mag Release, I had loads leftover from making BCARS)

• 1x AEG Trigger spring

• 1x M4 AEG Metal Trigger (OPTIONAL but highly recommended, may need to cut/sand trigger to get it working smoothly)

Electronics:

• 4x RCINPOWER GTS V2 1207 6000kv motors (3s) OR 4x RCINPOWER GTS V3 1404 4680(4s)/2850kv(6s) motors OR 4x Emax ECO 1404 6000kv (3s)/4800kv (4s) motor OR Brotherhobby Vy 1504.5 2950kv (6s)/3950kv (4s)

• 1x AM32 4in1 ESC (20mm mounting holes required, must be small, I've been using a NeutronRC 20/30 Hold Mini 45A AM32 4in1 ESC

• 1x Seeed XIAO rp2040

• 1x Buck converter/BEC (5V)

• 1x Neutron Solenoid OR 1253 size Solenoid (Please double check the thread and standoff size you need)

• 3x Subminiature Microswitches (Rev Trigger, Fire Trigger, Dart Detector)

• 1x RK097N 10K Rotary Potentiometer (3 pin version)

• 1x DRS4010 Rotary Coded Switch (Or similar size, MUST be 10 position and with shaft)

• 1x 1000uf 35v capacitor (Optional but recommended, fits in the Dart Guide)

• 2x XT30 Male Connectors (One for Battery, Another for easy ESC removal)

• 1x XT30 Female Connector (For ESC)

• 16 AWG power wires

• 26-28 AWG signal wires

• 3s-6s Lipo/LiHV (Size and voltage depends on stock and motor selection)

• 1x MS-GnK MOSFET PCB

• 1x MS-GnK IR PCB

Electronics without PCBs:

• 1x 1K Resistor (For MOSFET)

• 1x 10K Resistor (For MOSFET)

• 1x 5KP30A Bidirectional TVS Diode (For fast decay)

• 1x MOSFET (For Solenoid driving, FQP30N06L used, other logic level N channel mosfets should work)

Stock Hardware:

• 2x small springs (For locking latch, I don't have measurements for these since I cut down assorted springs)

• 3x M3 Nuts

• 2x M3x8mm Bolts

• 1x M3 Thumbscrew

• 2x Worker Stock Bars OR 2x 5mm x 250mm steel bars using the Printed Stock Rear and Protean Printed Stock Bars

You can switch out and use your own electronics if needed, if you want to use different motors, make sure to double check the measurements on the flywheels and motor mounts to see if they will fit. 

Suggested AM32 Settings:

This is for the NeutronRC AM32 ESC I have been using. A flight controller was used to flash ESC. You are welcome to experiment with settings as you please. 

Note the Motor KV, match that with the KV of your chosen motors, I think lowering this  gets the motors up to speed quicker, but I have not experimented with that much

Firmware has a few adjustable values at the top of the sketch:

You will most likely need to adjust Motor/ESC settings depending on your motor choices. Other settings have worked for me by default, but you are welcome to tune them yourself. Troubleshooting is available in the build guide.

Build Notes:

• I'd HIGHLY recommend getting the flywheel cage plates cut in Aluminium, .step file for this is included. If you are adamant that you want a FDM printed plates, print them in a rigid material such as Nylon.

• Cage mount front and Cage mount rear MUST be printed in TPU 95A shore hardness or softer. I have been printing these with 1 wall, 15% infill. This keeps them soft and in theory helps reduce vibration throughout the blaster. 

• Loctite your bolts into the motors, or at least periodically check they are screwed in. I have found that using the M2 Washers for the motor mount bolts have helped significantly in keeping the motors secure.

• I wired up an XT30 connection point to the ESC and used the JST Cable that came with my ESC for the signal connection. I highly recommend doing this for easy access and removal. 

• A slot in the Dart Guide is available for a 1000uf 35v capacitor, this is optional but recommended if you have ESC issues. 

• Some parts may need supports when printing, such as the receiver halves and flywheel cage, I will leave that up to you for support placement. 

• For the receiver grip, I highly recommend using a grip sleeve to help keep the grip closed together when a battery is inserted.

• All .stls have been orientated to how I print them, you may adjust this as you please.