M203 Grenade Launcher rifle

[doopydoo]

2in OD White PVC pipe from home depot will fit a grenade with a little relieiving from a dremel on the inside.

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1. I don't have a dremel.

 

2. I don't know what you're talking about, how can something that's already too big (40mm is 1.57inches) be made to fit something too small with a dremel?

[PheonixZero]

OD is the outer diameter, so that means the inner dia is tighter, probably tight enough to stop a grenade from moving around.

[doopydoo]

OD is the outer diameter, so that means the inner dia is tighter, probably tight enough to stop a grenade from moving around.

<{POST_SNAPBACK}>

Ah, sorry for my ignorance. About how thick is PVC pipe? This may yet work.

[PheonixZero]

Eh.. not terribly thick, probably around an 1/8" more or less.

[powelly]

How did you get 40mm piping? That's the main reason why the project's on hold.

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the main barrel is maybe 50mm which is bigger than i wanted, but the breach is 40mm exactly, it isn't how i wanted it to be originally but it works, i used a 40mm plumbing fitting (40mm inside diameter but it needed some filing down inside as there was a lip on the inside of it for the 2 pieces of pipe that go in there in plumbing. ill try find a pic of it.

[SPG]

You could buy some oversize tubing and sleeve it down.

 

So lets say you buy some tubing with a 1.75 inches internal diameter, and a 0.8 inch wall thickness. You cut two pieces the same length then cut one of them lengthways so there's a slot out of it. Then loads of hotwater poured down the inside will mean you can force one inside the other.

 

Voila correct size.

 

Of course you could always just do this for the breach and forget the rest of the barrel.

 

Oh and insulating foam is good for stocks. the closed cell pink stuff. very easy to cut and then just lay fibreglass over the top.

[renegadecow]

1. I don't have a dremel.

<{POST_SNAPBACK}>

 

Get one. Or a clone thereof. The ones made in china are cheap but has low rpm. You'll need one when you start fabricating the smaller parts.

 

You have a good idea here, its just that you'd want to make the shell replacement as simple as possible. Although material cost estimates are about $20, do take into account the cost of gas shells, which are about $35.

 

Using a second hand M203 plus some above-average wood skills, I was able to make this for a friend for under $100. I forgot to install sights though.

 

[doopydoo]

Wow, that's nice. I think I could do that, but the stock wouldn't be as fancy or pretty... I could probably align the wood to the launcher right though, thats what matters mostly... But the problem is that the launcher is $200, and even a second hand one which would probably be fine would be $100 at least.

 

By the way, what kind of wood and stain is that, and how thick of wood?

[renegadecow]

The launcher was a used JAC I think, and cost a bit under $100. I used radiata pine, 1" thick planks (2 planks side by side) so I could easily gut out the grip area where a 3/4" tube goes right through securing the launcher to the stock. I was still using varnish (walnut) when I made this, but half-stain Zar modern walnut will get you the same color.

[scoot_n_shoot]

Buy a dummy baton round from airsoft scotland, its only £3.50 (i dont know if you can get a similar thing in the us), it will fit in a grenade launcher ( the length might be different but the width is 40mm)

 

Great idea by the way- nice and simple!!! lol!!

 

http://www.airsoftscotland.com/acatalog/In...n_Supplies.html

[Baptiste]

I'm actually trying to build one too, similar to yours but you gave me some ideas as I have no idea how grenades exactly work. I do know that you have to somehow press the button on the back of the grenade, like in a revolver kinda. I got that right right? If not can you give me a detailed post of how grenades work.

 

One of my problems is that when you've put the grenade in the tube, will the grenade not risk just sliding out, or when pressing the trigger it may just push the grenade out of the barrel and not the button. I think you mentioned something about this in youre first post but I could not figure it out.

 

Anyway I'm poor and have no money so I'm still in the "planning" phase where all I need is some brains. So I saw you're diagram and I took the liberty to make V4, I though we could work together as I've found that were trying to build the exact same thing, with similar appearances:

 

 

As you can see in the barrel are 2 little black things that would hold the grenade in place and it would not fall out without of course blocking any holes of the grenade. The rest is basically what you came up except I though we could use rubber like material for the stock end for it to be more comfortable.

 

Then this diagram shows the technical parts:

 

 

The part squared in red is the thing that would hold the barrel straight when the grenade is inserted without holding it. I don't know what to call it.

 

In blue is the hinge that would allow the barrel to bend to insert the grenade.

 

Green are the things that would retain the grenade from falling out.

 

Purple is the iron sight.

 

Yellow is the whole trigger assembly with the rotating hammer and such and if you are sure that this will work, then it will be just fine.

 

Pink is the rubber stock end to be more comfy.

 

 

You got MSN Doopydoo? You think we could work together?

[Baptiste]

Okay it wont let me edit my post for some reason but I wanted to show a new diagram I've made, Personally I think Doopydoo's first diagram was best so I redid it:

 

And with the tech parts:

 

Squared in red would be the slider that locks the barrel in position when ready to fire and be slided off to allow the barrel to curve so you can insert the next grenade.

 

Squared in yellow is the whole trigger assembly with the hammer to strike the back of the grenade.

 

In purple are the iron sights.

 

Blue is the hinge that will allow the barrel to bend to reload when the slider is not in locked position.

 

The bits squared in green would be a little thing standing up to stop the slider from going any farther either way.

 

And pick is the butt stock with the rubber.

 

 

But here again we remain with the question how do we make the grenade not fall out from the barrel?

 

What do you think?

[scoot_n_shoot]

But here again we remain with the question how do we make the grenade not fall out from the barrel?

 

Buy 40mm OD plastic tube and dremel part of it for the grenade to 40mm, then it will stay put.

[scoot_n_shoot]

But here again we remain with the question how do we make the grenade not fall out from the barrel?

 

 

Buy 40mm OD plastic tube and dremel some of it to 40mm (enough for the grenade to fit comfortably)

[Baptiste]

But here again we remain with the question how do we make the grenade not fall out from the barrel?

 

Buy 40mm OD plastic tube and dremel part of it for the grenade to 40mm, then it will stay put.

<{POST_SNAPBACK}>

No I realised that the grenades have a little thing on the back of them larger than 40mm so they would not fall out when locked in.

[scoot_n_shoot]

No I realised that the grenades have a little thing on the back of them larger than 40mm so they would not fall out when locked in.

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you still need to dremel

[renegadecow]

And you probably meant ID, inner diameter and not OD.

[Onechance]

Didn't read through entire topic but thought this could be handy

Maybe you could email him for plans or something?

Sorry if its already been posted

[doopydoo]

It would be nice if he just sent me a bit of pipe...

[renegadecow]

You still haven't got one? It's just a 40mm PVC pipe. You can get those practically from any hardware store. Oh, and I might as well share as I'm going to build my own 40mm GL completely out of scratch too (unlike the bought GL + custom stock I showed you before).

 

1. red lines marked (1) on the cross section and front are flat, long pieces of plastic made to resemble the grooves (6~12) off a barrels rifling. Depending on what grenade you use (some have rounded tips, others flat) you will have to alter these specifically in length as to how deep the grenade itself goes into the barrel. These plastic strips will keep the grenade from moving forwards and are simply glued permanently into place.

 

2. small red squiggle marked (2) at the grenades rim is a thick, flat piece of sheet metal bent into the appropriate shape. This is actually copied from the design of an M203, which has 2 of these devices, but one should work fine. This acts as a clip to provide positive engagement when the grenade is loaded. It is to provide minimum tension as well as an audible signal "click" if and when a grenade is properly chambered/unchambered.

[doopydoo]

Ahh, i get it, all that stuff to keep it from falling out. Anyways, I think I said it before, 40mm piping is not availible at my local hardware stores, I like in america, where everything is in inches. 1.5 OD to 2.0 OD to be specific, where the grenade is about 1.68inches wide I think, so 1.5OD is too small, 2.0 OD is like 1.8 ID I think, too big.

[SPG]

For those in the US, why not shim it down? If you take a length of PVC pipe which is too large an internal diameter, make a single cut lengthways down your tube, you can then squeeze it in till it forms the right diameter.

 

Now mark how much overlap you need to cut off and remove this. You'll probably find that given the variety of wall thicknessness of PVC tubing you can find one, which will give the right internal diameter, and which will give a tight fit in a 2 inch external diameter tube.

 

You don't even have to do this for the whole barrel length just for the breech area, and if you inset it a little bit you've got your seat for the grenade's rim.

[renegadecow]

I think the 2.0" OD pipe will work with you. The ID may be a little too big for the 40mm grenade, but you can add spacers around where the "brass" part of the grenade is and just make the rifling or whatever stops the grenade from moving forwards, thicker.

Try checking THIS out for example. You can see from the pic that the chamber itself isn't smooth but has some kind of small ridges to keep the grenade from wobbling about.

 

If you choose the 1.5" OD pipe, you will have to heat-mold the grenade into the tube itself to make the impression needed to fit. Practically no dremelling required. This will be a much harder task and needs a lot of practice as well as a lot of pipe to practice on but will give you a seamless barrel. You can heat-mold PVC by exposing the part to be manipulated over a gas stove flame (don't let it touch the flame). Then, while the chamber end of the tube is pliable, carefully insert the gas grenade in it to expand the plastic and form against its shape. Heating must be even all around the circumference of the pipe so that the molded chamber will be concentric to the barrel.

Heres a SAMPLE of what you can do with PVC heat molding given enough practice. The foregrip (minus G&P folding foregrip) was once a 50mmOD PVC pipe. Only 4 other small pieces were glued to it.

[soap]

i had this problem with my home made launcher (i finished it yesterday ) i wanted to use aluminium piping, but the supplier only used external diameters and in inches so i had to have a bit of a guess at sizes of internal diameter, luckily it turned out well. i will try to find out the external diameter.

i used a simular design to the madbull one as it is for mounting under my m4.

 

soap

 

EDIT: the piping has a 1 3/4 inch external diamiter and the thickness of the sides are 2mm wall thickness leaving an internal diamiter of 41mm, and it is a perfect fit, hope this helps.

[Meathead316]

i recon this is a pretty cool project, a rifle that fires grenades, whats not to like?

 

i definatly think you should go for a rifle looking design (more like the badger one) than the m79. using a similar loading technique to the m203 i think would be best, but pulling the shell cover backwards which cocks a hammer at the same time i think would be good, that way you dont have to hold the trigger for it to work.

 

one other thing. you can already get these types of launcher kinda), so how about making something a bit different, like a double barrel one, or maybe even three barrels? all firing at once, the enemy would either run or soil themselves!