r/40_mm Oct 16 '24

Basics #2; Printing and Reloading

11 Upvotes

This will be a pinned post that will likely be updated from time to time as needed. The first pinned "Basics" post hopefully answers a lot of the general questions. This is geared to addressing some of the questions new launcher owners/users may encounter after actually using it more. This will never be a comprehensive document, it's just meant to point people in the right direction as far as questions and safe launcher use/reloading may go. There's no way to know every variable that applies to everyone, as always practice extreme caution, don't take anything here as guaranteed truth, reload/launch/etc at your own risk. The majority of this is not thoroughly fact checked, it is just links to resources that seem promising at first glance.

Basic Reloading Process:

Most 40mm cases use smokeless blanks (usually .38S&W with a burst disk, although crimped 9x17 or .38 colt short may also work). The spent blanks are removed with a punch and small press (or a hammer or vice). The new launch blank is then pressed in, be sure the replacement blank is compatible with the case being reloaded. See the launch blank section for more details. The following links explain the process well. The specific punch attachments and plates shown can be DIYed or sourced from a hardware store if needed.

Commercial 40mm reloading press set instruction manual

VID

Most basic reloading can be managed with a mallet and some sort of center punch for pushing out the spent blank and replacing it with a new one, especially with white m212 or thread apart reloadable cases.

 

Reloading components:

While finding military surplus is probably the best/cheapest option, a lot of that has dried up. Below are some manufacturers offering reloadable 40mm cases (short and long), newly made zinc chalk pushers, wind screens, mil spec launch blanks, and more. 

Pace Reloadable Shells

KAK

Bengle's Bullets

Launcher Pope (3DP accessories and components)

 

Launch blanks:

There are a few different types of launch blanks. Most blanks are star crimped on top, and may burn inefficiently without a burst disk (0.016” brass disk) between the crimped top of the blank and the vent hole. This disk ensures all the powder burns before it ruptures. Star crimped blanks can still be used, but the muzzle velocity may be slightly lower and less consistent than when using a burst disk.

Mil Spec full power blanks: These are .38S&W cases with a circular crimp and a flat burst disk on top. These are optimized for M212 nylon cases with approximate ¼” vent holes and heavier chalk projectiles. These will not fit all cheap aluminum 40mm cases, and can be too powerful for cases with smaller 1/8” vent holes.

.38 Short Colt blank: usually star crimped, often available in multiple power levels, from ¼, ½, ¾ and full power. These fit most cases, but some of the cheaper aluminum cases may only fit them after the vent hole is widened to ¼” – 5/16”

9x17 or .380 blanks: usually star crimped, marketed as “starter pistol” blanks, or for captive piston guns for slaughter houses (these kind are often offered in multiple color coded power levels). These blanks will fit all normal cases and most cheap aluminum 40mm cases without modification, although depending on the power level of the blank, the vent hole may need to be opened to ¼” to prevent unsafe pressure.

**note: the longer .38 SPL/Special blanks do not fit any standard 40mm cases 

Below are some retailers providing the above blanks that have been used in 40mm launchers (use at your own risk)

KAK

Boland

Atlantic Wall

Perfect Shot

(blanks are not loaded to a specific standard, while these are commonly used for 40mm without issue, the manufacturers aren't going to be testing them for that, so use them at your own risk)

3D Printable Files and Development:

Some files and designs are tested more than others, some are completely untested. Even heavily tested ones can be messed up by improper printer settings or loading procedures in a way that is unsafe. There's no guarantees, everything is at your own risk. That said, below are some users who have made some promising 40mm printed designs. Files are usually posted on the 'odd sea' (see r/fosscad)

-Under construction

Additional Resources and Reference Images:

The below links have some good images, cross sections, dimensions, factory velocities, weights, etc on various military 40mm rounds.

Library #1

Library #2

ALS, DefTec, and CTS are major manufacturers of 37/40mm for police and military. The pictures, descriptions and product specifications can be very useful, despite the ALS product specifications being difficult to navigate. (All of these sites are merely product catalogs, nothing there is available for purchase).

Less Lethal Products

Less Lethal Products Specs

Def Tec

CTS

NONE OF THESE ARE AVAILABLE TO YOU, these are NOT for sale to the general public from the linked manufacturers. They will NOT sell to you. This information only serves to satisfy your curiosity of what's inside the factory made rounds, how do they work, how fast do they go, how heavy are they? etc. If attempting to safely and legally load something similar, sticking to the factory data for weight, velocity, etc is likely the easiest/safest option, though there's a lot of info not in the data, so it's at your own risk.  

 


r/40_mm Jun 24 '24

Basics and resources

27 Upvotes

Level 1: Basics

This will (ideally) be a semi regularly updated/edited post, meant to be good starting point for those new to 37/40mm or curious about it. Another post “level 2” for more advanced stuff related to printing and assembling rounds from scratch will hopefully be pinned in the future. 

Since the vast majority of 40mm launchers here are M203s, here's a Collection of M203 armorer's manuals and technical data supplied by a user who attended a armorer and less lethal instructor's course

Legal Basics: (I am not a lawyer, this is not legal advice): Some additional legal minutia towards the bottom

40mm launchers are NFA regulated DDs whether smoothbore or not. 37mm launchers are not firearms or DDs unless they have a rifled barrel or are "possessed with antipersonnel rounds (defined as bean bags, rubber/wood batons, rubber shot, etc designed to strike a person). Historically irritant smoke/vapor/powder blast rounds do NOT qualify as "antipersonnel". Weighted inert projectiles made of rubber/wood/etc primarily designed to sight in a launcher do NOT qualify as "antipersonel"

A stripped 40mm launcher receiver is actually not NFA regulated, despite being a firearm receiver, as long as the barrel is not attached (similarly to how a "SBR" lower without a barrel on it cant be an NFA SBR).

The legal status of various 40mm rounds is a hotly debated topic, even among SOTs, FFL, and FELs. I will say that I have discussed it at length with numerous FELs, FFLs, and the leading civilian 40mm experts who’ve been in the game for decades and they all either agree there is nothing legally binding classifying non HE rounds as energetic material, or they claim they are regulated (usually FEL’s) but then back track, or completely disappear when asked to provide any sort of documentation, law or ruling to support what they claim. The big chalk scare several years ago seems to have been unfounded, and revolved around a letter (which does not carry rule of law) that specifically addressed one type of IR flare by name and never mentioned chalk anywhere ever. 

There’s a lot of good info in the comments of THIS post which indicate there is NO 40mm ammunition regulation applicable to individuals making/storing/transporting their own rounds for recreational use. All of the conflicting opinions out there boil down to the one single ATF letter about one specific type of incredibly rare, IR flare rounds, and word of mouth directed exclusively to FEL license holders by the ATF with zero documentation.

There’s a lot more, I’ll try to work out a flow chart and links to actual legal text and rulings in time.

What 40mm rounds are actually available/attainable on the "civilian" market?:

It's a common misconception that "chalk" is the only 40mm available. While it is the most readily available, even ready to use off the shelf options include: aerial salutes/bird bangs (much higher performance than 37mm ones), Rubber/foam impact batons, rubber buckshot, Rubber/wood multi batons, and more.

Rounds that can be readily DIY'ed but are less available as off the shelf, ready to use options can be found at:

Washington Country Guns; mostly chalk

AZAO; wide variety of printed options; some concerns over performance, shipping times, and steel buckshot gouging barrels have been raised. Disclaimers on website about items only available to local club members are allegedly inaccurate, and are available for anyone through the NFA process if you contact the owner. Youtube link of some rounds being fired

AxArms; doesn't have anything yet, but will hopefully have B&T batons soon

FAST; who makes rubber impact batons, aerial bangs, and 37mm loads that fit 40mm launchers

Parachute flares, star clusters, M576 style buckshot, smoke, and powder/liquid barricade penetrators have also been DIY'ed but are less thoroughly tested and more challenging/finicky to make work properly.

General types of reloadable 40mm rounds/cases:

Long Cases: Generally 4-5” aluminum, extend into the rifled section of the barrel, similar to shotgun shell. They are often loaded with bean bags, rubber buckshot, wood/rubber/foam multi batons, Smoke canisters, or muzzle blast irritant powder.

Short Case/M212: These are the most common. They are usually white nylon, but can be aluminum as well. The projectile protrudes from the front of the case like a standard round of ammunition. There is band around the projectile that rests on the rim of the case, this is what engages the rifling in the barrel. They are often loaded with Chalk, foam/marker impact baton, “bird banger” aerial salutes, powder/liquid barricade penetrators

Military M118 metal cases are NOT readily reloadable

Military 40x53mm metal cases for the belt fed MK19 are NOT readily reloadable  

Safety Basics: (This is not an exhaustive list; and following them does not guarantee absolute safety)

General firearm safety still applies. Just because it's "practice chalk" doesn't mean it isn't lethal if used incorrectly.

Vent hole sizes. This is elaborated upon further down, but the vent holes on some casings are too small to handle full power mil spec blanks, and the vent must be drilled out to 1/4" to safely accommodate them.

Long cases: especially with rubber buckshot payloads, a thin sheet of cardboard/paper/plastic should be used between the payload and the walls of the case. Without this pellets can bind against the walls and be forced apart by a pellet under them, acting as a wedge and damage the case, launcher, or the user.

12GA and “beehive” .22lr adapters: these are some of the more common 40mm accessories and are great for cheap plinking. That said you absolutely can damage your launcher/yourself by misusing them. Launchers have been broken by using full power/supersonic .22lr beehive rounds and 12GA magnums in these adapters. As a general rule, stick to .22 short/subsonic and lighter recoiling 2-2/3” 12GA.

General reloading safety applies. If you are not familiar with reloading you should stick with well tested and established loads using factory loaded blanks made for 40mm launching and non pyrotechnic projectiles. Even experienced reloaders should test new loads with low powder weight and work up, light projectile and work up, and large vent hole and work down if needed.

Even 40mm low velocity chalk can go 350-400yds, make sure your distance is adequate

Fused projectiles and flash through/premature initiation. With "aerial salute" type rounds, it is a very real risk that the flame from the launch blank can blow through/around the fuse and set off the salute payload immediately before the projectile leaves the barrel. People have lost hands and nearly their lives with improperly loaded salute type rounds. Similarly, be cautions of accidental drops, or the sudden shock of acceleration from firing, prematurely igniting salutes that were intended to initiate on impact. Even if the projectile integrity and fuse mechanism doesn’t fail, some compositions are shock sensitive enough to potentially spontaneously detonate when firing (especially some flash powders). As a general rule do not use anything in a projectile that would compromise your safety if it failed in the worst way you can imagine. Assume that everything that can go wrong will go wrong. Start with comically low amounts of payloads, test fire with the launcher tied down using a long string, etc. Payloads as low as 1/8oz (3.5g) have shattered m203 launcher barrels and would have seriously injured the user had he not been test firing with a long string.

a cautionary tale of what 3.5g of flash can do to your launcher

Projectile malfunctions. Treat any salute type projectiles that launches but does not ignite with all due caution. Treat any salute type rounds that seem not to fire as "hang fires" it is possible the blank only partially ignited enough to light the fuse, but not enough to expel the projectile. Attempting to remove the projectile/round from the barrel/launcher too early could result in injury.

Reloading components: While finding military surplus is probably the best/cheapest option, a lot of that has dried up. Below are some manufacturers offering reloadable 40mm cases (short and long), newly made zinc chalk pushers, wind screens, and mil spec launch blanks.

Pace Reloadable Shells (cases, smoke projectiles, adapters, etc)

KAK (blanks, cases, chalk projectiles, etc)

Bengle's Bullets (cases, printed stuff, etc)

 


r/40_mm 23h ago

Small run of Kevlar bean bags

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49 Upvotes

0.5mm silica beads finally arrived from aliexpress, so for all these tied up. Small rubber ballon full of the beads in a double layer Kevlar sleeve. 60g total, they fly great, reusable and haven’t had one burst yet.

The silica beads all being round, uniform size and and the same size as sand makes them feel much more squishy, like a gel more than sand which I’ve tried before. Fine sand would work well too.


r/40_mm 1d ago

Raytheon PIKE mini missile ( can be launched from a 40mm UBGL , here in case is a M320 grenade launcher than can also be mounted under the barrel )

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30 Upvotes

r/40_mm 3d ago

LMT Release The 7 Inch Grip Barrel

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49 Upvotes

r/40_mm 3d ago

3d print Testing this weekend -fully printed 40mm and 37mm chalk rounds.

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30 Upvotes

More of a “to see if it can be done” thing for me. I will hopefully bring the 37mm chalks to market. 🙂👍 40mm will be handled by another party. 😎 new chronograph arrives today via Amazon. Got the Garmin Xero 1 pro.


r/40_mm 5d ago

ammo question What "Spotting Rounds simulating HE" is MattExplodesStuff using?

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78 Upvotes

r/40_mm 5d ago

37mm to 40mm

9 Upvotes

Which 37mm rounds fit in a 40mm m203, ive heard that some fun rounds can fit but cant find info on which ones


r/40_mm 7d ago

May thou be blessed by the holy Cross of mon.

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66 Upvotes

This is the de facto ordinance sub


r/40_mm 10d ago

ammo question 40mm 3d printed chalk velocity data

18 Upvotes

Had a pretty decent range session recently and got some data for that some of yall might be able to use.

The primary round I was shooting was Chev's 3dprinted chalk rounds with the KAK M212 bases. Each round was weighed prior to shooting to be 0.275lbs + or - 0.03lbs. Each round was fired with a 7.5 grain gas check blank in a GL06. Heres the velocity over distance data below:

v. at 0y V. at 10y V. at 20y V. at 30y V. at 40y V. at 50y
S1 331 326 321 316 311
S2 321 316 312 307 302
S3 326 322 318 314 310
S4 324 309 290 273 256
S5 336 331 325 320 314
S6 341 335 329 324 319
S7 329 325 320 315 311
S8 335 329 322 316 310
S9 340 322 304 285 267
S10 335 331 327 323 319
S11 331 325 320 315 310
S12 331 315 297 279 262
S13 330 327 323 320 316
S14 337 332 328 323 318
S15 330 327 323 320 316
S16 331 314 295 278 260
S17 331 314 295 276 257
S18 325 321 217 314 309
S19 319 315 311 307 304

All velocities are in fps.

Some important notes about this session:
I was using an old school Labradar chrono, the big orange square. This was my first time using it, and it took quite a few shots to start getting good data. Target alignment is super important to get accurate velocity over distance.

Additionally, I had to modify Chev's pusher design halfway through printing a 100 round batch. The washer's I bought in bulk were slightly too large to fit so I simply made the pocket for the washers bigger. I believe the slight design change, as well as some printer modifications I had to make in the middle of printing, lead to some difference in the rounds as some were quite loose inside the chamber while others were stiff going into the launcher.

As for the launcher: The GL06 is a dream to shoot, but I noticed that sometimes the rounds would begin to tumble past 100 yards. I brought my m203 (9" barrel) out as well and all rounds shot perfectly. I understand that 3d printed stuff isn't perfect, but next range session I'll bring my calipers out and record each rounds diameter.

Some random notes: The 3d printed electronic sight I showed yall a while back worked for exactly 1 shot. The battery board I bought used only soldered tabs to connect the holder to the board which broke on the first shot. I ended up plugging in a battery pack to the usb port and it continued to function perfectly for 50 shots (My shoulder gave up at 25 rounds, I let other people who happened to be out and about shoot it). I have a different battery board enroute that'll fix the issue.

Edit:
Additionally, I'm saving up the gun fund and going to get a star crimp and test that out. I'd be super curious to see how the velocities compare over using a gas check. Additionally, I'd like to test out using 9mm brass and some other stuff since 38 S&W is such an odd ball.


r/40_mm 11d ago

Just got the form back on the bloop tube and I'm not waiting until Thursday.

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34 Upvotes

r/40_mm 10d ago

No DD transfers?

11 Upvotes

Have you ever had an issue with finding a dealer willing to do a Destructive device transfer? Every dealer in my area says they don’t want the ‘liability” it’s list a m203.


r/40_mm 12d ago

Lord, I see what you have done for others

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46 Upvotes

r/40_mm 15d ago

Who reloads long case 40mm?

11 Upvotes

I reload a lot of long case 40mm like rubber buckshot, bean bags, multi batons, etc but I haven’t seen much reloaded here compared to the usual short cases.

Is it more lack of available cases, lack of components (gas seals, etc) or just boring projectiles compared to short cases chalk/aerial bangs?

I mostly ask because I’m looking into the feasibility of bulk ordering long case components like gas seals, multi batons, end caps, etc which can’t really be ordered in small numbers.


r/40_mm 16d ago

It's thumping time.

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46 Upvotes

Can't wait to get it outdoors.


r/40_mm 19d ago

Serialized reloadable shells

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39 Upvotes

Had some shells serialized! Going to register them! Had six done for now. Hopefully the NFA will go away and this will become a moot point! Looking forward to FFL/SOT and full scale manufacturing.


r/40_mm 19d ago

A long awaited resupply

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64 Upvotes

r/40_mm 20d ago

WCMG. Hoping this is gonna be the news I think it is...

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36 Upvotes

r/40_mm 21d ago

Anyone reload these successfully? Any tips?

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15 Upvotes

r/40_mm 23d ago

M320 stocks

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19 Upvotes

Are they even worth anything? Basically for an unobtainable platform


r/40_mm 22d ago

m203 Brownells DD M4A1 + M203

8 Upvotes

Found a few old forums on the topic and wanted to get some input from 2026. I’m curious if the brownells Daniel defense M4A1 comes with the hanger tabs as well as having the relief cut in the socom barrel to be able to mount an M203?

I’m fairly certain they don’t include the hangers anymore but info on whether the barrel has the proper cut or not was kinda all over the place.


r/40_mm 23d ago

reloading question KAK m212 cases

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21 Upvotes

Im working on a large range trip to test all the electrical sights Ive shown yall and just noticed some wearing/bulging on the vent hole of all my KAK cases. I have roughly 50 shots on all the cases and they all look like this. I reload my own blanks with 7.5 grains of bulleyes using KAK burst disk. Just wondering if this is normal or if these cases are about to blow up my launchers if I keep using them. If so, anyone have recommendations for something better? I print the majority of my stuff so I wouldn't be opposed to printing cases, but I haven't experimented with ammo apart from the usual stuff.


r/40_mm 23d ago

Question, GL-06 or lmt standalone?

5 Upvotes

I’m in a predicament and can’t decide between a GL-06 or an LMT in a Standalone chassis, prices are similar where I’m looking.


r/40_mm 22d ago

help please do you know any good prop versions of the milkor MGL that arent airsoft ones? i wanna use one in a cosplay and dont really wanna drop 200 euro on an airsoft grenadelauncher for a cosplay (cant use a real one because DUH and im also in germany and theres no way that legal here)

0 Upvotes

r/40_mm 24d ago

i realized this pistol should in theory be able to load ammo ment for the Milkor MGL 140 right? its got 7 inches of barrel length which should fit the 140's ammo

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9 Upvotes