M72 LAW Airsoft TagInn Launcher (DIY for $70)



the four pieces that I broke it into minor improvements but the quality is much higher see those came out pretty good clean not a lot of cleanup lines that I have to do so this should work out pretty good added a couple connector spots here kind of like Legos so it clip together but the idea is that I might have to sand them down every once while you see the 3d printers you know they're good but they're not perfect and so we got a little bit of overage on here and you end up having to send them down but this should all walk together so you'll have them walk together like this and you put a couple screws in to pin them in and that'll hold it in place but we'll have the four pieces lined up so these are the four the reprints and the four pieces that were reprinted and so you'll see how they stack up here so looks something like this when they're all put together nothing you crazy but a lot of fun looks like a law m-72 launcher and so today I'm going to show you how to put these together which I go look at these four pieces here I'm getting cleaned up we'll cut up the ABS plastic what you'll need for this project obviously a 3d printer so you need the 3d printer to print out the major components and then also the internal components so I'm just having to throw on them all and a little tray here but you'll see so like this for example it's the front sight from flip-up sights this would be the trigger lower trigger mechanism holds a the rod aluminum rod and fires the tagging show the trigger itself plastic trigger this is lever release for the extension to flip up sight front release upper trigger mechanism this holds the gas refill gas fittings beneath this holds the trigger mechanisms in place underneath the rear flip up sights this was a second extension release I ended up extending this after doing the first prototype and playing with it seems like I needed a couple more millimeters this way it can hold it to better the tube was sliding out past the extension release so this one's actually needs to get recycled this is a guide for the rod so that way the rod has some stability less chance of it bending or flexing you'll need this is actually the spring cap so this holds the spring in for the trigger mechanism we've got here the cover plate plate for the gas fill area on the problem I had with this one on this print this warped a little bit too not sure it was really cold here in Spokane and so the you can see it's a little bent but it could have been because of the ambient temperature and the garages in the 40s the printer heat plate is usually 60 degrees Celsius and if they didn't adhere very well as it cooled to start to warp a little bit so I could hit this with the heat gun and try to straighten it out this is a cover plate for the front sight release the gas fitting so for the gas fittings we're actually going to need this one here this will be from the grenade out so you can see here I was already test fitting this but essentially this is another guide right this'll hold the aluminum rod which will push the firing pin in the middle of the tagging show so you see that there and so this cover bolts on this sleeve here is the shell holder so this grenade shell holder should be perfect size for this this is tagging around or tagging show the co2 version so way you can use the refilling the portable refill fist or another cheap one I just use a cheap one this gas fitting here and which I'll lift out so this is our replacement actually I'll go that back to show you guys this is the original this is what your gas shell dome that comes in like don't come in something like this so you'll need the a regular tagging challenge or any other co2 or green gas grenade shell whatever kind of show you want to use but one that we can replace the gas fill valve with and so you'll see here this one is a male 10 32 by quarter-inch push-to-connect for the gas shell and then this will be to receive the quarter-inch lines line and one to putting the fill valve here in the end here so that way you can fill the grenade launcher shelf without having to take the shell out of the grenade launcher itself so you need those I've got a spring here for the front sights release small spring and again I'll list in the description all of the information on the parts that I ended up picking up that end up having a punished project you'll see these roller pins here so we've got these roller pins so this would be for the front sights and the extension release so I've got three of these these are my half-inch four millimeter screws that I use throughout and I'll include a link to those too and a couple of our set screws in there so miscellaneous hardware it was probably about five dollars were the hardware from Ace nothing fancy but it's all general hardware store stuff that you can use and so we'll be able to put this together today using all of those pieces so first thing I typically do once the 3d prints done and you've cleaned up and rolled all the temporary supports get everything organized here you're going to want to have your tools and tools well in addition to the tools other materials we need obviously aluminum rod so here's the aluminum rod just round typical aluminum rod I've got a quarter inch here about 36 inches it's the one I picked up from Home Depot this guy some slider our galvanized adjustable bracket please this for the expansion release also acts as a secondary safety for the trigger so you can see this extension so slides in and out I've got the ABS plastic piping itself so two-foot abs is to protect from home depot pre-cut two inch by two feet and then these are the couplers for it two inch couplers act as end cap so you'll be using these on the ends here when we build it so you see alright so you're gonna want to make sure that you've taken some time to stand down all the edges the high spots anything that might hang up the function of the launcher or catch on you know your skin or clothes make sure all the components are tight-fitting they're snug but don't break them and if they're you don't force it if it's a if it's hard to connect just send it down a little bit more I'll give it a little bit of clearance that should be all you need in regards to the rear section this section is extremely important that it functions and all the components can move smoothly within the rear section of the rear lower trigger mechanism and the lower trigger mechanism slides forward and backwards that's what actually pushes the firing pin on the launcher or the tagging around and so this absolutely needs to move freely so you want to make sure that that is moving smoothly push it it'll push up against the upper trigger mechanism and so if any either of those surfaces are rough it won't slide smoothly so they need to slide smoothly against each other make sure that there's no edges or anything there that it's gonna hinder the movement our next steps gonna be to cut the ABS tube you're going to cut it one side needs to be 13 inches long and one another the other half needs to be 11 inches long makes it pretty easy by a pre-cut 2 foot section from Home Depot of ABS to remember this is the 2-inch pipe don't accidentally cut your 1 1 and 1/2 inch pipe the 11 inch section is the section you're going to use for the front now you're going to end up notching it and so the notch that we need to make is approximately one and a half inch by 8 inch and that's going to have a little bit of an extra a little bit of an extra notch there down at the bottom right corner and that's going to be for us to ensure that the gas valve has clearance next test fit everything make sure that all the clearances are acceptable I'm just showing you here how I came up with the size of the notch obviously it's a rough cut if you guys need to stand out or cut out more feel free it's it's not a structural or performing any other function but I just cut ours with the dremel tool which we could get a good blade and then cut through it the ABS plastic is always the thing ever run into learn the problem with it is sometimes it melts onto itself and so you got to tap it every once while with a hammer just to break out the section that you're working on next thing we're going to do is install the gas shell the grenade shell into the grenade shell holder there's a spot for a set screw that little spot for the set screw goes towards the rear of the grenade shell that will sit on the there's like a lip within the grenade itself so that'll keep it from falling out or sliding backwards you'll see two other set screw spots we're not using those at this point make sure that the grenade shell could slide freely to the tube when you push in the set screw here what you'll notice is that the set screw will keep the grenade from going backwards and falling out of the sleeve the grenade shell holder itself the sleeve there will size correctly so that way the grenades won't go forward do not over tighten the set screw which you'll notice as the set screw when it starts getting tight it'll actually bump out the plastic shell holder and once you do that if you do it if you push it out too much you won't be able to fit it in the 2-inch abs – it should be snug but you need to be able to push it too freely the next piece we're going to install is a grenade shell retainer grenade retainer and basically this is a guide or a guide for the aluminum rod that pushes on the firing pin you're going to want to test fit make sure it's working good the other important pieces the gas fill valve needs to be towards the bottom of the shell that way you can access that fill valve we're going to be replacing that later with a different fill valve that has a push to connect make sure you install the set screw next we're going to replace the fill valve you can use a flathead screwdriver to replace the fill valve just turn it out counterclockwise make sure this shell I'm using is a co2 shell make sure you have the right shell for what you're building I chose the co2 so I can use the portable co2 filler but you're going to replace the fill valve with a it's a 1032 by a 1/4 inch push to connect gas fitting this one's a male version and so it should thread right in make sure you get some teflon tape on there helps keep it sealed otherwise you might end up with some liner gas leaks it should thread right in make sure that you tighten it by hand just give it a couple turns with a wrench once your tightened by hand don't over tighten it these are pretty thin threads and it would be easy to strip out or snap off the fitting if you're not careful so do not over tighten the four gas fitting and then we're going to test it out as well so you'll be able to hear if it does need to get a little more tight or a little looser what you're going to do with the female fitting the gas fittings you're going to install the original gas fill valve in it same thing at some teflon tape to it and thread that in just until it's snug if you over tighten it you'll notice the o-ring will bulge on the top and then you'll end up with a gas leak so don't over tighten it here you can see I got a quarter inch macro line from paintball-gun make sure you use the right macro line they have different psi ratings I don't want to see anyone get hurt so make sure that your macro line is properly rated I have seen because the co2 is up to 850 psi typically I've seen macro lines burst when they're not appropriately sized so make sure you install the grenade retainer on the grenade show it takes two screws and the two squares of the two forward most screws you'll see how it lines up tighten those it down with the allen key I sometimes I pre thread it just so that way I know that it'll mesh up pretty well with the receiving side so install those two screws and then you'll slide the grenade shelf forward until the grenade show hits the housing the the front section housing the green housing part and they should line right up once you've got the grenade shell flush toward you see it pushes up against the green housing install the two last screws and the two last screws do a couple things that connects the front with a section that holds the flip up sight the midsection that has a CCD logo on it and then it also holds the grenade in place don't forget to install those two screws because it holds the grenade in in place if you fire without the two screws there it might cause some trouble here I've installed the gas fittings on the ends of the quarter inch macro line just testing it make sure I've got enough line and that I can actually maneuver the gas fitting to fit in the guest fitting holder I designed the guest fitting holder a bracket basically into the side of the housing there and it should fit snug right in there with no problems next step install the retainer basically the other half of that gas fitting holder that little bracket there and it just takes two screws it's a little bit of a pain if you have the macro line in because the macro line is stiff but it just takes two screws and a little bit of patience once you get the two Allen bolts in there the the gas fill valve should be stable the next item here we're taking a look at the rear section we're going to connect the two halves of the rear section and right now is that there's just dry fit but we want to see how the whole rear section goes together work on the trigger mechanism the lower trigger mechanism portion here it has the quarter inch aluminum rod and so we'll push the aluminum rod towards the back of the lower trigger mechanism I just tapped it in with a rubber mallet and made sure that that was snug there's two spots there four set screws if you need to install a set screw to hold the rod it should be tight enough that it doesn't require it but if you need it you can the rod should be cut approximately 300 35 millimeters in length and that way it has enough length to push in the grenade shell and fire it you're going to want to notch the 13 inch section of ABS piping you're going to make the cut about proximately 4 inches from the edge make a 2 inch by 2 and 1/2 inch cut and this will provide clearance for the trigger mechanism into the rear section make sure you test fit everything the rear section has a retainer it's a pretty thick plastic that specific spot is one of the potential weak spots of the design so that's why I've reinforced it make thicker and it has four screw locations and make sure you use all four of those but basically the you'll see the feed through the tube here the trigger rod and make sure that it's clear with the lower trigger retainer the next step you don't want to get a spring find a spring for the trigger mechanism the spring I use is approximately 5.1 millimeters in diameter and approximately thirty five point four millimeters length I use a universal kit from amazon and it has some of the springs that I need most of the time it has the springs that I need and so it's been sufficient I didn't have to order any custom Springs or anything crazy and so I just test fit the spring in here to make sure that it seats correctly and that it also has enough tension to push the trigger button back up after I fired the launcher make sure that the spring moves freely there's a little spring guide basically built into the design in the rear section you'll see that the spring will go right there in the hole make sure that it can move freely through there if it lines up anywhere make sure you sand down any edges the spring needs to move freely so that where the trigger returns to the original position after you fire the launcher here you're going to want to connect the upper trigger mechanism the lower trigger mechanism and the retaining cap and feed them all into the rear section of the launcher there's basically the entire trigger assembly here's the upper trigger mechanism and so make sure you orient install them with the orientation correctly the orientation should be as shown here the upper trigger mechanism the lower trigger mechanism and the retainer install the upper and lower trigger mechanisms at the same time you can feed one side in snap it together make sure it's sitting flush and that all the components are moving freely next step install for those screws that hold that retainer in place it's critical that you install that like I said that takes the majority of the force when pushing up against the tagging shell if this area is not reinforced it will snap if you try to shortchange the structural screws that are there after we're done installing that we're going to test the movement on the trigger mechanism itself there's always going to be a little bit of play in it and so that's why we have some guides for the trigger run you'll see in the front section that holds it stable so that way that deflection doesn't cause any issues the next piece I'm going to take a look at install the spring for the trigger and so you push that through the guide like I said there's a hole there it lines right up with the lower trigger mechanism and so I'm gonna do is feed the spring through and then there's a spring cap that you have 3d printed compress the spring the spring cap itself has a an indentation basically to hold the spring on the cap side so compress it with whatever you need to I used a wire pick and compress the spring and then push the snap in place and so after you've pushed the cover in place you can secure it with two screws it just has two little screws there they take a little bit of time to install but it'll hold the trigger spring appropriately for you know a long time of use after the spring caps install we're going to tell the trigger mechanism the actual trigger button itself trigger button itself goes up top only needs one screw to hold it in place and you'll see that snap it in first it should pressure fit on top of the upper trigger mechanism and then thread the single screw through right after you're done installing the trigger mechanism into the rear section you're going to want to test the motion on it make sure that it's moving freely the aluminum bar should move forward approximately six millimeters or so and return the spring that you installed should cause the trigger to return on its own feed it through the rear section PBS pipe see how it lines up and then the next thing we're going to do is finish assembling the rear section in its entirety there's only two screws left and you just assemble this the two screws to connect the two sections together alright so the next thing you're going to do is you're going to basically have two halves complete double check that the trigger function still works always test everything after you make a modification that way you don't have to tear the whole thing apart you're going to test fit the two sections together make sure you use the rod guide that's built in and that way everything is actually lined up the way it's supposed to you see that it's right there in the middle outside of the grenade shell and so they let me rod should feed right through there that'll help guide the rod to make sure that it's actually pushing on the firing pin if the rear section doesn't sit flush you're going to want to trim it and you can trim it as needed well that's complete and everything's flush you're going to start drilling the pilot holes in the ABS piping for all of the mounts for all the screws that secure the front section and intersection to the actual ABS pipe so use a 3/32 drill bit and follow all the existing holes that already designed into the 3d model here you'll see that I wasn't able to get the two sections to sit flush so I did have to trim off a little bit from the rear section looks like maybe half an inch or so I just cut it a little bit test fit and cut a little bit more funny too for the most part it's designed so you have a little bit of leeway there's a little bit of slack and the precision and how long the ABS pipe needs to be so shouldn't mount right up with minor modifications well when the entire launcher is assembled you should be able to test the gas fitting and so I'm going to do a dry fire here and just test it out sometimes you have to push the trigger a few times to reseat and reset the actual grenade shell itself and so there you go once it's receded it'll hold a co2 like it's supposed to when you're done testing or adjusting any of the gas hoses for leaks or anything like that then you're gonna install the cover if everything is holding tight install the cover it's just two screws you'll see there's a hole pre made and designed so that what you can fill the gas shell you don't have to drill anything in the lid there and next step after that we're going to start notching the back section the back ABS pipe making sure that that extension release lever can do what it needs to for that to function correctly you're going to need a spring so I'll measure out where that where the release lever lands on the pipe router that out and then pick the appropriate spring line it all up and check the fit next we're going to need to make sure you pull out your roller pin and test fit that you know it's going to be a snug fit and it's designed to be that way and also roller pins aren't exactly round and so make sure you've got a round file utilize a round file to smooth out any edges that way it'll make sure that the roller pin can actually move in and also hold the levers and we're gonna have to do the same thing for the flip up sights and this rear extension release tap it in with a nylon hammer there's a little bit of extra on there just trim that off with a cut-off wheel on a dremel tool so that way it's appropriately sized you could look for a shorter roller pin from the hardware store I just bought three of the same kind and didn't have to waste more time shopping check the release expansion release make sure it works with the spring and then we're going to start sizing up the actual extension pipe itself so taking a look at where the extension pipes how far forward it can move before it actually hits anything this scenario looks like we're gonna have about eight inches on the extension pipe and so mark the extension pipe and then cut it as needed make sure you test fit everything as usual see how it will fit or won't fit on this side I can see where I'm starting to hit the extension release along with the trigger mechanism it so this gives me idea where I need to start notching the extension piece so that way it clears the internal components what you end up with after you measure everything out and end up filling everything in you get an extension piece that's notched out and the notch is going to be approximately it's going to be approximately two inch by four inch cut and then have two small half inch by half inch square notches cut out of it and that's for the extension release itself here I'm just going to show you how I made the notch is kind of how I came up with the rough cuts so you can see how I was measuring it out and continually trimming guess and check and test fit it until found the right solution and the right cuts of what I needed just a little bit of time for our next step we're going to want to install the rear sight rear a flip-up sight cover on top of the extension tube and cap um and to do that you just drill two holes utilize the existing pilot holes from where the screws should go and drill those into there you want to try to flush it up to the back portion of the end cap as far back as you can but try to keep everything a lot more flushed out all right when you've completed installing the rear flip up site cover we're going to move on to measuring out and cutting up the extension of slide bar help stabilize it also makes it look similar to the existing law and so you'll see that the existing side bars of these one side of it can overlap the other and that's the one we want to go inside of the rear section of the launcher that little extra one inch two inches of metal actually act as a second safety for the launcher so that way doesn't accidentally go off so when the extension is collapsed it blocks the trigger from depressing the tag in show alright once you're done measuring out the extension bar you're gonna want to make sure you cut off the little tabs that are left at the bottom don't remove the vertical piece that has the hole in there because we're actually going to attach the screw we're going to attach through that hole to the both the extension pin cap and the rear section of the launcher every slider bar maybe a little loose and so make sure you check everything out I'll file any rough edges it's gonna need to slide into the rear section pretty easily now we doesn't get caught up on the rear section housing so make sure you test everything just you know file down items that are little oversized or sand them down when you're done installing the extension bar slider you're gonna want to start working on the sights so the flip up sights we have a front and rear fluff up site the first thing we want to do is install the front sight latch it also has a spring that it uses so you'll see there's a little nub on the latch that nub needs to beat orientation the orientation of the nut needs to be upward that way the spring consider Assyria be seated correctly on it make sure you install the front sight latch cover the cover holds of the spring in place it also keeps that front sight latch from falling out of place and so it should fit it's pretty snug but it should block the spring and the actual sight release from coming undone so it'll be a little loose but it should have some play in it but it'll hold the sight no problem once you're done installing the front sight latch you start working on making Springs and focusing on installing the actual flip up sights themselves again just like with the rear extension release you're gonna make sure you sand out any of the holes where the roller pins are going to go into and so that way they have clear movement making Springs is a little challenging it took me a while to get used to it but now you can make Springs with piano wire and so if you buy something I got some off Amazon again always have the parts listed below in the description here but I ended up making our drilling out a bolt or roller pin and that way I had the right diameter for the spring and then wrapping the spring around until I made a torsional spring that I needed for the flip up sights now there's the extension stabilizer that I printed out what this does is help make sure that the extension piece itself doesn't wobble too much because the one and a half inch pipe to the two inch pipe has a pretty significant gap stabilizer will hold that make sure that doesn't move the way it's seated it'll seat right in front of the rear cap on the two-inch pipe so install that check the fit like I said it'll be really tight what you'll notice is that the ABS the one and a half inch ABS pipe that we notched out the diameter that is significantly smaller and slides easy once you get towards the back of the extension pipe it starts to rub on the stabilizer and so you might have to sand down either the actual one and a half inch pipe or the stabilizer itself or both so that way it moves smoothly in and out the main thing is we have a tapered one and a half inch pipe and so that ends up causing trouble still working on a solution for that and could be something I do in the future to improve the design but for right now I just stand it down the extension pipe so that way you can move to the stabilizer with no issues and that concludes the build if you've enjoyed this please feel free to share it feel free to also send me a message or leave comments if there's something else you want me to take a look at designing and building I really enjoy designing and building this I also had the infrared laser version that I built for Pegasus milsim this was spawned after that was designed from a couple other airsoft players in the community I wanted something to fire tagging rounds if you got something you want to build feel free to hit me up I'd love working on this type of stuff and would love to help continue to enhance the gameplay that we have for airsoft community thanks for everyone for watching and hopefully have fun and be safe we'll see you on the

2 Comments

  • Jess Rosales

    April 14, 2019

    Could you please show the function of the launcher it looks amazing but I want to see how it works after it's assembled

    Reply
  • proxxy04

    April 14, 2019

    Hey man love the build, is there a way you could make me one? I’ll pay for all the parts and materials and of course for your time.

    Reply

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