Here you go - I am guessing you are looking for under barrel mount ones. They are still a little pricey since ammo will be hard to come by be sure to have deep pocket diving into this.

https://otbfirearms.com/lewis-machine-and-tool-m203-40mm-grenade-launcher/

Do what the movie prop people do and mount a 37mm or 39mm flare launcher on an AR-15, like what was don in Scarface.

Colt AR-15 with Fake M203 grenade launcher (a.k.a. "My Little Friend")
Tony Montana (Al Pacino) uses a full auto converted Colt AR-15 with a Fake M203 Grenade Launcher attached during the final battle. In one of the film's more memorable moments Tony yells out "Say hello to my little friend!" and blows a door down with a 40mm grenade, killing several of Sosa's men. Also of note is that he has two magazines taped together 'jungle style'. After expending his first two magazines, he inserts a single 30 round magazine before the end.

The grenade launcher used is a 39mm smooth bore "Fake M203" used to imitate the M203 in the 1980s before the advent of the Cobray CM203 Flare Launcher, and is also used in films such as Predator and Heartbreak Ridge. The Fake M203 grenade launcher was custom made for use on the film and the firing pin has been removed to prevent the use of live rounds. The launcher was fabricated because the property master was unable to locate any live firing grenade launchers for production. He had this M203 grenade launcher hand crafted (not molded) by the studio prop department. The launcher was created with an extra large trigger guard and wider ribbing on the barrels than are found on the traditional M203 design.

Originally an M16A1 was used with the grenade launcher and the full auto converted AR-15 was substituted after cinematographer John Alonzo determined that the AR-15’s firing sequence could be timed to synchronize with the Arriflex cameras, which would result in elongating the duration of muzzle flashes seen on film.

TRIVIA: Not only is the launcher used in this movie the same type used in Predator, but the particular launcher used in Scarface is the exact same launcher used in Predator. http://www.imfdb.org/wiki/Scarface_(1983)

Cobray CM203 37mm Launcher
Cobray Co. (originally of Smyrna GA, but now currently of Westhope, ND) built many smooth bore 37mm Flare launchers that were smooth bore copies of the M203 grenade launcher back in the late 1980s (originally known as the CM2037 IMP). Versions were made by SWD (the predecessor of Cobray) and RPB, as well, but Cobray was the last, and most successful, company to sell the launchers. Throughout the 1990s, several improvements were made in the construction and cocking lever as well as shorter and longer length barrels.

The Cobray CM203 37mm flare launcher is not a grenade launcher per se as it is chambered in the 37mm civilian caliber, which lethal rounds are not manufactured in and which is not compatible with the 40mm military caliber. It can only fire riot control "grenade" rounds such as gas and smoke, purchase of which is usually limited to law enforcement buyers. However, since it looks like an M203 grenade launcher it is commonly mistaken for one in films on this site. It was built for civilian use as an under slung flare launcher commonly mounted under M16/AR-15s variants and other rifles. It is preferred for most film use over a genuine M203 mainly because, unlike the M203, it is not considered a "Destructive Device" in the U.S. (unless possessed with 37mm direct-fire ammunition such as baton or beanbag rounds, or with a 37mm-to-12-gauge shotgun adaptor) and not subject to NFA regulations. Such weapons are thus more expensive and difficult for film productions to acquire. http://www.imfdb.org/wiki/Cobray_37mm_Launcher

- Updated Model CM203 mounted onto an M16A1 - 37mm flare. In the 1990s Cobray updated their CM203, adding a sturdier curved charging handle, and an M16 Style safety. Also the trigger guard is now screwed in at both ends and is thicker. Later models would have larger mounting blocks and some variants will have mounts designed to attach to RIS rails.

The Cobray CM203 37mm flare launcher can be distinguished from the Colt M203 based on the following:

1. The M203 is a 40mm launcher capable of firing multiple purpose rounds, the CM203 is a 37mm launcher built specifically as a flare launcher for civilian use.
2. The CM203 has an M16 style safety switch (on later models), the M203 does not.
3. The CM203 lacks a second safety trigger in the front of the main trigger, which the M203 has.
4. The CM203 Flare launcher's trigger guard is more squared when compared to the M203.
5. The CM203 37mm had an external cocking lever on the side of the receiver, the M203 cocks on closure.

- Short-barreled Cobray CM203, not attached to a rifle - 37mm flare

Buy a LMT 40mm reciever from a FFL. Register it as a Destructive Device on a Form 1. Get approved, then buy a 40mm barrel. Easy, takes about 1 month to do.

Why 40 and not a 37 like the Havoc from Spikes? You can enjoy flares, smoke and noise rounds without the hassle of destructive device, NFA of '34 nonsense (though you'd want to check your local laws and make your own decisions). Just make sure not to possess any "anti-personnel" rounds for it, which would obvious anti-personnel stuff as well as less-than-lethal types of stuff.

>>109279
because this.
https://www.gunbroker.com/item/842475457
and
>pic related
>30 rounds in 2.4 seconds and then four (4) .410 shotshells.

>>109280
40MM Hornets Nest Round

This round allows you to load and fire four (4) .410 shotshells with the use of one large pistol primer from your 40MM grenade launcher. This original reloadable round was repeatedly tested using four (4) 2½" .410 shotshells.

We recommend 2 ½" in the LMT and 3" in the M79.

Manufactured from high quality aluminum and then hard coat anodized. Firing pins and components manufactured from tempered 17PH stainless steel.

Our new, improved design incorporates a replaceable primer pocket by using a cut down .45 ACP brass casing. It is installed with a press-fit.

Shotshells produce 32"-34" pattern at 10Ft (2 ½") from the Muzzle of 12" LMT.

This is an awesome addition to your 40MM munitions.

>>109281
That's freakin' rad. I've seen hornets nest style adapters like that for .22LR but never .410 shotshells.

>>109290
Here's the older 40mm Hornets Nest shell of 10 .22 LR rifled barrels in an aluminum case.

Neat, huh?

US 40mm M575 buckshot, canister & Hornet's Nest grenade launcher loads.

If you're knowledgeable enough you could make your own HE rounds but you would have to register every single fucking one of them with the ATF and pay a tax on it.

Acquiring an M203 is relatively the easy part in all of this.

>>109297
No doubt. It would probably be better to just use a 37mm flare gun M203 replica attachment for a kitted-out AR and just launch flares out of it.

Firing buckshot or anti-personnel canister or flechette dart rounds out of a flare gun is not recommended!

37mm launchers are not supposed to be used for is anti-personnel type rounds unless they are registered in advance as a destructive device. When a 37mm launcher is registered as a destructive device, it can be called a grenade launcher and because the proper laws and regulations have been followed. https://exotic-firearms.com/blogs/news/7916933-why-register-a-37mm-launcher

I guess the laws about short-barrel shotguns govern flare guns or grenade launchers that fire shotgun rounds.

- A 40mm Lewis Machine & Tool (LMT) blooper that loads special shells that fire four .410 shotshells.
https://lmtdefense.com/firearms/gl

40mm pistol?
They even have a shorter barrel version...
The Shorty Forty.

>>109299
I know you know this and know more about this stuff in general with your big computer brain but that's one thing I actually appreciate about the logic of the NFA.

If I buy a full auto transferable machine gun, I don't also have to pay the tax stamp for a short barrel because the weapon's status as a machine gun supersedes the need for non-machine gun legal statuses. Same with destructive devices. If it's a registered destructive device, who cares how short the barrel is?

The lawyers who authored this legislation could have been a lot MORE pants-on-head stupid when they wrote all this up and I'm glad they weren't.

  >>109301
No just wondering about big flare guns that might be able to load and fire special anti-personnel shells such as metal hulls that fit shotgun shells or multiple pistol or rifle rounds. The 27mm flare gun may be modified to look like a grenade launcher (as the one used in the 1983 movie Scarface), and you can attach it to an AR legally, and you can fire flares, smoke rounds or rubber ball training munitions out of it, but when you start loading anti-personnel rounds (Hornet's Nest or shotgun shells) that flare gun becomes a destructive device and you don't want to get burned on a weapon charge like that.

https://www.brownells.com/shooting-accessories/duty-gear/safety-amp-warning-equipment/m203-37mm-launcher-prod118458.aspx
LMT M203 37mm Flare Launcher https://youtu.be/CkU33L4MjK4

Another use for old flare guns is to turn them into Star Wars blasters, such as with this British WW1 Webley & Scott No.1 Mark I 1.5-inch (37mm) flare gun from 1914, later used as a police riot gun (for firing tear gas or rubber baton rounds), and then gussied up into a Boba Fett blaster.