Airsoft M72 LAW rocket launcher

Using an airsoft 40mm grenade shell for the reservoir and valve system, build a nerf launching LAW for about 60 dollars plus the cost of one airsoft 40 mm grenade shell.

WATCH THE VIDEO!!! - It explains how the launcher works.

Edit: People keep asking about the Strap/Sling. it is a 1 inch wide cotton webbing strap purchased at a local fabric store. Buy about 1-2 yards. Also buy velcro and 1 inch plastic buckles.

Edit 2: People STILL keep asking about the "Locking Mechanism". Seriously, it is nothing but a piece of plastic. But since I get questions on youtube, here, forums, private messages and email, I decided to make a video. WATCH the video in STEP 7.

EDIT #3: If others have a method to use a DIFFERENT GRENADE, Please Post a comment. Then we can Collaborate on making an instructable for using a DIFFERENT GRENADE. I have brainstormed methods of using other grenades but they all BREAK my Rule OF K.I.S.S. With that said, I ONLY RECOMMEND THE MAD BULL XMPB4 or the S-THUNDER GRENADE. Don't Ask me about other grenades.

Step 1 How it works

Illustration of what is happening inside.

My sorry excuse of a drawing of what is going on side the launcher.

Pictures are in sequence.

Color Code

Red = Grenade, 40mm type
Orange = Nerf Mini Vortex
Green = Green Gas
Blue = Valve
Black "T" = firing pin.

Picture 1 = Launcher ready
Picture 2 = Pin presses Valve
Picture 3 = Valve Open and Gas Explodes Out.
Picture 4-5 = etc....

Comments

[gnazaire]

Is there any substitute to fiber glass???

[MrTinkerer]

carbon fiber

[cdaniel2]

Just out of curiosity, would the launcher be able to fire loaded 40mm grenades instead of nerf balls? Like, if I loaded the grenade and left the nerf ball out, would it damage the weapon?

[MrTinkerer]

not sure

[cdaniel2]

This is still me. I've also noticed that it uses a different type of grenade. So, if I loaded a bb-type 40mm grenade, instead of the multipurpose grenade and Nerf rocket, would it damage the fiberglass tube?

[boredom99]

Hey where do you find nerf balls I already checked walmart they didn't have it and I don't know if toys r us has it. I know that Toys r us and everything discontinued their sale of nerf vortexes for some reason so where could you find those?

[awesomesauce24]

how many times do u wrap the wax paper and mylar around the pvc

[MrTinkerer]

3-5 layers. It depends on how thick the material is. We want a tight fit but we also want the pvc tube to be able to slide. the fiberglass shrinks a little as it cures.

[yish1919]

where did you get the gas can or online? cuz i buy things online more then in the stores

[MrTinkerer]

local store. i dont like paying for shipping.

[yish1919]

Which air grenade is better, or is all of them are the same and have the valve on the back?

[blslespaul]

what is yours or anyones average range with the S-Thunder grenade? Im building several LAWS for friends and some of my contacts throught the airsoft manufacturers have stated that the XMPB4 has been discontinued through Mad Bull... Im only getting about 20yds with the S-Thunder grenades as the power source, yet we played 2 weeks ago with my LAW and I got a 175yd launch with the XMPB4 :)

[searl2]

I used an ignition system of a BBQ sparker and static-guard. It seams to ga farther that the green gas and it dosent take time to warm up. Just out of curiosity, why did you use green gas?

[MrTinkerer]

I dont want an ignition launcher. This is a non-fire, non-ignition instructable to make it universally field legal. As far as I know most legal paintball and airsoft fields will not allow potato canons in their games. That is why I am using green gas in a non-ignition way. Just playing safe.

[Inverted_Spectrum]

Cool! If only nerf wasn't so restrictive of power, then kids will be shooting each other with stuff like this (although injury can occur more, hmm...).

[The3rdPunch]

I'm confused does it shoot bbs or a NERF ball?

[MrTinkerer]

Did you read Step 1?

[PJPEEJ]

is the grenade reusable? i don't wanna spend another $80 on only 1 grenade. And also, are there cheaper ones? I plan on making this instuctable. Its totally awesome :D

[MrTinkerer]

Yes and yes. Google "S-Thunder grenade". I think 50-60 bucks.

[The3rdPunch]

Hey could you use 40mm PVC or CPVC instead of an expensive airsoft gernade?

[MrTinkerer]

I don't know what a 40mm PVC, so I don't know. Besides, my design is field tested and works great the way it is.

[PJPEEJ]

sorry if im being annoying but how much would it cost in total and when u fire, does the grenade thing launch too?

[airsoftchase]

ok so I want to make your launcher but i want to use the s- thunder multipurpose grenade ,but i want to be able to shoot bbs and nerf rockets..any suggestions on making the grenade able to be taken out during battle so i can reload

[MrTinkerer]

no

[airsoftchase]

what is the greenish tape stuff?and where can i find it?

[MrTinkerer]

Green self adhesive felt.

[airsoftchase]

will the s-thunder fit as well as the mad bull in the coupler?

[MrTinkerer]

most likely yes. Remember the s thunder and the mad bull is a replica of a 40mm grenade shell. With that said, they will mostl likely have the same diameter.

[pablotheillegaltaco]

What is the locking mechanism for is it to hold the metal bar in place?

[MrTinkerer]

no. It is to lock the tube in the extended position.

[MrMadmonkey4]

i made one of these and its so awesome!

[MrTinkerer]

:)

[General Eggs]

You almost forgot that the Mad Bull XM PB4 has a fill valve in the back. lol

[MrTinkerer]

???

[General Eggs]

I just thought that was funny what you said about the grenade.

[MrTinkerer]

You mean in step 9... Yeah. Was trying to be funny, but is was really a response to dozens of the same question here and in youtube..."why the xmpb4?"

[General Eggs]

I hate it when people ask questions like: how do you make it? (I have seen that on an instructable) that can be answered by reading the instructable.

[airsofter4]

would pvc work just as good for a replacement of the fiber glass?

[MrTinkerer]

There is no combination of PVC sizes where one PVC pipes outside diameter (OD) fits perfectly into the inside diameter (ID) of another pipe. Trust me, i did NOT want to use fiberglass, but there was no PVC or ABS solution that was simpler than just using fiberglass.

[airsofter4]

how did you get the end of the bar shaped like that inorder to press the m203 grenade?