The M203 and M320 Grenade Launcher

Greetings Me Droogs and Droogettes!

Time for another round of Sergeant’s Time Saturday!
Because of my birfday gift, we’ll go over one of the more common small arms in the military’s arsenal.  The older M203 and the newer replacement, the M320 40mm Grenade Launcher.

The M203 is a rifled, single-shot 40 mm under-barrel grenade launcher designed to attach to a rifle.


Now, the 203, on it’s own, off-rail so to speak, looks like this:

It’s a single shot, breech load that opens like a pump-shotgun.

As seen here with a blue-tipped training round, you can see how the round is ‘fed’ into it.  It’s been in service since 1969, originally with the SF Kids who wanted a 40mm weapon that was mounted ON the M-16 as opposed to the separate weapons system, the M-79 “Bloop” Gun, which was a standalone 40 mike mike that looked like a retarded single shot shotgun.

It’s a aight weapon.  Meant to give the Infantry a bit more ‘bang for the buck’

Its designed to break through windows and exploding inside where bad guys might be.

Interesting side note:  In Iraq, the accuracy at longer distances, the 203 wasn’t that great… leastways for the EOD kids who were using it to make IEDs do the whole ‘sympathetic detonation’ thing.  So, someone somewhere found a bunch of old M-79, rebuilt them, and gave ’em to the EOD folks…The M-79 has a longer barrel, ergo, more rifling, ergo more accurate.  And with IEDs?  Accuracy means a lot.  It was kinda cool to see a Nam Era weapon still banging away in 2005 eh?
So, part of the problem with the 203 is the age (most are really old, and therefore they tended to be ‘loosely’ mounted with a lot of ‘play’ thereby adding to the accuracy issues.  They also tend to have extraction issues, getting the spent round out usually involves a cleaning rod down the muzzle after firing ’cause the extractor was and is a flimsy piece of shit.
Ask me how I know
So, Big Army went out and contracted with H&K and bought the M320

This’s it in standalone mode.  It’s got a pistol grip, features a spring loaded side load, and is double action on the trigger as opposed to single action on the 203.  It comes issued with the retractable stock, and a digital rangefinder which helps to figger out if the target is in range.  Lase and Blaze apparently.

That being said, the “Gee-Whiz” factor equals mor weight.  Never liked by the guys carrying it over distance. 
It too can mount on the underside of the M-4 as this:

OK, now, to be honest, the guys I talked to who I issued these to (yeah, I was on the initial fielding for them back when I was doing the Depot Level Small Arms Repair thing) had a love/hate thing going on.  For one major issue was the bulkiness of the fucker when it’s underbarrel.  Purely loved it in self-standing mode tho… more accurate, and the load/unload of the round meant a far faster increase in round output downrange.

Faster Boom Boom is sometimes a good thing.
It loads like this:

Now, unlike the 203, the 320 when you hit the ‘eject’ button, the 320 literally springs open and spits out the spent shell.  Like violently.  Compare this to the 203, where you push the release, slide the barrel forward, and IF you don’t have a shitty extractor, the empty casing falls out.

HOWEVER, If the extractor is a pile of feces, the shell stays in the barrel, necessitating a cleaning rod down the bore to punch the case out.
Pain in the ass in combat n’est pa?
Yah.  I think so too.  But like I said, the grunts I talked to have a love/hate.
Pros 203:
Cons 203:
Shitty Extraction
Wobbly Mounts (even after an update kit)
Pros 320:
Speed of reload
Spring loaded ejection
Hi Speed sights
Can be used as a standalone weapon w/accessories
Cons 320:
Shorter barrel, (less accurate?  not sure -yet-)
Can be used as a standalone weapon (but requires a LOT more bullshit to carry)
The sights on a 203 and a 320 are the same… except for the Gee-Whiz 320 laser-rangefinder.
One is a Leaf sight

Good for about 200-250 meters.

Mounts on top of the top heat shield, tho nowadays the front heat shields are all picatinny rails…hence why the mount has a ‘quick’ crank mount.
The other, which is good to 400 meters, is the quadrant sight

as you can see, it’s got two flip out sight posts, and the thing slides up n’ down for aiming.  Set the slide to whatever estimated range the target is at, aim thru the peepsites, and >BLOOP!<

HE on target.
I have both for my Havoc Launcher (a bringback from Iraq 10 years ago) When I found them new in the box back then, it was “Hmmn… wonder if’n I’ll ever need grenade launcher sights?”
Talk about pack-rattish and forward thinking Aye?
Good thing I did… new in-the-box quadrants are like $200 bux…
So anyways…
Now… onto ammunition… Couple of important things
Main issue:  If you capture a bunch of ‘linked’ 40 mike mike ammo….
The ammo looks thusly:
Thats a belt of Mark-19 40 mike mike Grenades in a Launcher. 
(Specifically a grenade machine gun)
The bolt weighs in at over 35 pounds

It’s a beast and in order to make it a “40mm Grenade Machine Gun” the grenades have, shall we say, a lil more “OOMPH!”

As in if and IF yer retarded enough to load one of these into yer thin-assed lightweight man-portable single-shot grenade launcher, then hey! Nice knowin’ ya!

Reason for this is in order to ‘power’ the recoil on a MK-19, it’s like 12 times the amount of pressure…
Which means a 203 or 320, if firing a MK-19 grenade will catastrophically fail
Like “Earth Shattering Head-Removing >KABOOM<
Ugly as fuck IMO… YMMV
Trust me, I know of what I speak, I’m with the High Command.
Now… feeding this thing, I stole this directly from the FM:
Ammunition (Low Pressure) for the M203 Grenade Launcher, 40mm
1. (M433) High-Explosive. Dual Purpose Round. The HEDP round has an olive drab aluminum skirt with a steel cup attached, white markings, and a gold ogive (head of the round). It penetrates at least 5 cm (2 inches) when fired straight at steel armor at 150 meters or less, or, at a point target, it arms between 14 and 27 meters, causes casualties within a 130-meter radius, and has a kill radius of 5 meters.
2.  (M406) High-Explosive Round. The HE round has an olive drab aluminum skirt with a steel projectile attached, gold markings, and a yellow ogive. It arms between 14 and 27 meters, produces a ground burst that causes casualties within a 130-meter radius, and has a kill radius of 5 meters.
3.  (M583A1) Star Parachute Round. This round is white impact or bar alloy aluminum, with black markings. It is used for illumination and signals and is lighter and more accurate than comparable handheld signal rounds. The parachute attached to the round deploys upon ejection to lower the candle at 7 feet per second. The candle burns for about 40 seconds. A raised letter on the top of the round denotes the color of the parachute.
4.  (M585) White Star Cluster Round. This round is white impact or bar aluminum alloy, with black markings. The attached plastic ogive has five raised dots for night identification. The round is used for illumination or signals. It is lighter and more accurate than comparable handheld signal rounds. The individual stars burn for about 7 seconds during free fall.
5.  (M713) Ground Marker Round. This round is light green impact aluminum with black markings. It is used for aerial identification and for marking the location of soldiers on the ground. It arms between 15 and 45 meters. If a fuse fails to function on impact, the output mixture provided in the front end of the delay casing backs up the impact feature. The color of the ogive indicates the color of the smoke.
6.  (M781) Practice Round. Used for practice, this round is blue zinc or aluminum, with white markings. It produces a yellow or orange signature on impact, arms between 14 and 27 meters, and has a danger radius of 20 meters.
7.  (M651) CS Round. This round is gray aluminum with a green casing and black markings. Though it is a multipurpose round, it is most effective for riot control and in Urban Operations. It arms between 10 and 30 meters and produces a white cloud of CS gas on impact.
8.  (M576) Buckshot Round. This round is olive drab with black markings. Though it is a multipurpose round, it is most effective in thick vegetated areas or for room clearing. Inside, it has 20 metal pellets, each weighing 24 grains, with a muzzle velocity of 269 meters per second. The round has no mechanical-type fuse.

My personal fave is the M576… Big assed super-buckshot round… good in-close weapon on hordes-o’-hajjis.  

Yeah, I ain’t right.
So, there ya have it.
Hope you Enjoyed it.
More Later, I Remain The Intrepid Reporter
Big Country

By BigCountryExpat

Fuck you if you can't take a joke. No one gets out alive so eat me.


  1. 5 December, somebody — not me, never — mentioned this blog on ,Rawles SurvivalBlog.

    The poster issued a warning to snow-flakes to cover their ears because somebody here is potty-mouthed and irreverent to sacred institutions.

    And he often uses the rationale "I ain't right", so that right there should qualify as a subtle hint.

  2. Good summary. Like you the M576 is a favorite.
    No experience with the H&K; did quals with the 203 when they weren't so old and wobbly (come to think of it I wasn't old and wobbly then either) but still much prefer the Granddaddy of them all, the M79 which is still in the inventory in some units.
    Boat Guy

  3. I carried and shot both the M79 and M-16A1/M203. Loved the M79 for it's ease of handling and shootability, it hit what you were shooting at. Fantastic weapon. Then we were headed for overseas deployment (again) and they issued us brand new M-16A1 and M203's. Headed off to the M79 range and fired our old reliables, then switched to the new wonder guns. Boy were we disappointed, these things handled like an over weight 2×6, ungainly and hard to anything with. We fuk'n hated them! BUT, on the plus side, you still had a rifle to fight with and a grenade launcher for secondary. It's proven itself in the 45+ yrs since I got my first one, and I imagine there's guys who now hate to trade them off for something new and improved. However, I'd still kill for an M79.

Leave a comment

Your email address will not be published. Required fields are marked *