40MM Gas Grenade Maintenence/repair guide (Pic heavy)

[Coz]

Ok so a few people are asking about maintenence and repair of 40MM nades so i thought id give a guide a go.

I have used a Dream army 120rnd Grenade for the demo

First things first the gear you will need.

Silicon/gear grease
PTFE Tape
Flat headed screwdriver (wideish blade so not to ruin fill valve)
Spare bearings (i used 4mm)
O-rings/seals (not pictured as i didnt need any)
Silicone lube
Can of gas
Grenades (Derrrr)



Next find out what the problem with the grenade is .

Make sure you reset the 40mm First.
Insert gas as normal.

If the gas spurts straight out again it is most likely a lost bearing.

If it has a slow leak listen to where the gas is coming from.

If its from the valve then its probably just a dry seal

If its coming from the BB holes themselves then its most likely the o-ring on the core thats dry.

Dissasemble the grenade by unscrewing it in half,do this over a towel incase any Bearings fall out, remove all components from inside (Core and any loose bearings,spring and primer)

Then unscrew the fill valve

Contents should look something like this.



Next check that any o-rings are not split/damaged, if they are you will need to replace them.
If they are just grey or powdery looking then they are simply dry
Blast them all with some silicone spray.Even better remove them and put them in a small shallow bowl with silicone oil in for a few hours/overnight.

Wrap some PTFE around the threads on the fill valve this will help keep the seal a bit more gas tight


Now onto the core.

Pictured below is a bone dry core.The bearings dont stay in when it has no grease on it (some have captured bearings)



Take your little finger and dip it in/scoop up some grease and slather it on the inside make sure you fill the holes


Keep the core up right and carefully place the bearings in the holes, then put more grease on the outside portion of the bearings.The aim here is to get the bearings to stay put without falling out.


I then put grease inside the lower half of the greanade


Next comes reassembly

place the Primer in the base, place core into position (keep upright at all times to reduce chance of losing a bearing) then place the spring inside the core(placing a bit of grease on the end helps it stay put)then screw the 2 halves together


You hould now be good to go

Pro arms 48rnd pom(these have captured bearings so theirs less chance of ever losing them)



Vanaras 60rnd aluminium & pom (these are self reset ones with captured bearings)


Pic of reset mechanism


Obviously some grenades have a fill valve at the bottom (Some S-thunder,Madbull ect) but they are basicaly the same.

I hope this has helped and any feedback on guide is appreciated.

[Froggy]

Re: 40MM Gas Grenade Maintenence/repair guide (Pic heavy)

Helps a tonne, thanks!

[Montesa77]

Re: 40MM Gas Grenade Maintenence/repair guide (Pic heavy)

Sticky it :D

[Dude666fx]

Re: 40MM Gas Grenade Maintenence/repair guide (Pic heavy)

Brilliant guide, all leaky grenades now fixed.

Many thanks! :D

[VOLK]

Re: 40MM Gas Grenade Maintenence/repair guide (Pic heavy)

Hi, does anyone know where i can buy replacement fill valve for Dream Army grenade? Fill valve on these grenades has much finer 5mm thread than standard grenades (fill valves).