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Let's try something different...

Rather than me being all snarky and showing off I can stump you by controlling the variables (hardly fair) - I'm just going to slap this up there and let *you* guys show off what you know about what this is and how it works, vice "Can you figure out that this is an elephant when all I show you is a cellular slice from a polyp inside it's trunk?" like I usually do... Hey, I know I'm mean - but you keep coming back, so, we're like co-dependent, right? Don't forget to explain *why* a feature is there, not just that it's there. The whole purpose is to inform the curious.

40mm grenade

Extra credit if you figure out the proper nomenclature and nation of origin. I'm going to leave the comments open - but be honest - put your answer/description down and *then* read everybody else's. Block copying from a manual is okay, if that's how you achieve positive buoyancy for your bateaux, but I'll bring the best original answer (in my humble opinion) up into the post and leave it for the archives... just in case there's any egos out there who need a stimulus.


Okay, you guys need some help. How about the flip side? This is what SezaGeoff saw this morning.

The flip side

Bet it doesn't look like you expected on the inside... but the answer to why it *isn't* the M406 (like Doug thought) is clear to the true grognard. And Doug, aside from color - there are only two (related) things that cause the M406 to differ from this round.

Update: This is the M407 - the training version of the M406 HE round. The difference? Aside from the color of markings? The "ball" portion of the grenade. It's not serrated on the inside for fragmentation purposes, and it wasn't loaded with HE. The M407 was in turn replaced by the M781, which had a plastic projectile filled with a marking powder.

SezaGeoff, first out of the chute (and with the second pic to get him started) was the most thorough of you.

The fuze? It's an "all-ways" fuze - with a set-back and spin safety system that didn't allow the grenade to arm until it was a safe distance away from the firer - not that just shooting someone with the grenade wouldn't distract them... even if it *didn't* explode.


Well, it appears to be a grenade launcher round, constructed on the hi-lo principle, where the propellant is in the small chamber at the bottom, and restrained by a brass sleeve. This lets the propellant get a start up at high pressure, and then it bursts the sleeve through the holes shown into the main chamber. The pressure drops enough to give the grenade a firm push without busting either the gun or the firer's shoulder. M79 launcher and ammo But I am not sure about the fuzing of the grenade - it looks almost like a timing mechanism, and they won't let me play with that sort of stuff!
Sigh. I blew it. I put the wrong pic up. That was *supposed* to be the *after* pic. Geoff - I've saved your answer, and I'll put it back up later. (OW!) [sound of foot kicking desk]
lol snarked by self. It doesn't get worse does it?
Ok, I will go with the obvious. 40mm grenade. US origin. Not really any "belt" marks on it, so it isnt for a MK19 so it must be for a M203 or M79. Silver tip with OD body doesnt tell me what type it is.. so I will go with HE.(High Explosive)
Must.Show.Restraint... Must.Not.State.Obvious.... omgican'tstanditfallicfallicfallic!!!!!!!!!!!!!
LOL And here I thought the conventional wisdom was that guys were sex-obsessed!
Um, isn't that s'posed to be phallic? The PG-17C doesn't mind that spelling and usage... and, boy, W-K, if that's what you expect in regard to that... they grow 'em short and squat where you live!~
I was spelling "fonetickally" John.. hoping that I would get past the PG17C. I figger'd you dig me on "phallic", since I get in-trouble-fied for saying "well, $hit". harumph..... As far as short and squatty goes... as long as he knows how to use it, I'm good! Being hung like a bear doesn't do anyone any good if you don't know what to do with it. Oh... fd... you mustn't have attended many Castle Cuddle Puddle parties if you think that only the guys around here are obsessed! hehe.... *winks, and slinks back up to chandelier perch to watch the boys ponder over John's Whatziss*
I'm not real sure about the color on the projo, but if it's gold and not silver, I'm inclined to M406 HE 40mm M79/203 round of U.S. manufacture. I think there's an M376/M386 or so as well. I don't see any green, which strikes me as not quite right. You'd think I'd remember this, I fired enough of 'em in RVN (M203).
Heh - I'm waiting for people to give me details (like the lamented SezaGeoff's post) about how they work... Or are all of you guys who use 'em the "I don't care if it's magic, s'long as it works!" type? And Doug, you are actually *very* close on nomenclature... but not quite there.
"I'm waiting for people to give me details (like the lamented SezaGeoff's post) about how they work..." How it works is more or less conventional ignition for a center-fire cartridge, but the explosive rounds are spin-armed, which is to say that they need to be fired and traverse a certain distance before they arm, something like 20 meters I think. Thus, they cannot be dropped, thrown or otherwise used for their intended purpose without some other fusing (if improvising a mine or something). Single shot, the M79 is break-open, the M203 a forward sliding tube under the main weapon (say, M16 or CAR-15) with a separate trigger and sights. My rig (and a heckuva' John Wayne picture) is here: I'm on my way out the door for S. America at the moment, so will leave details on nomenclature to those with a lil' more time. It looks long for N M433, so maybe M381/M441? "The firing pin strikes the primer, whose flash ignites the propellant in the brass powder-charge cup inside the high-pressure chamber. The burning propellant produces 35,000 psi (2,461 kg/cm≤) chamber pressure, which ruptures the brass powder-charge cup at the vent holes. This allows the gases to escape to the low-pressure chamber in the cartridge case, where the pressure drops to 3,000 psi (211 kg/cm≤) and propels the grenade from the muzzle at a velocity of 250 fps (76 mps). The rifling in the barrel causes the grenade to rotate. The grenade's 37,000-rpm right-hand spin stabilizes the grenade during flight and applies enough rotational force to arm the fuze."
Ah - Not fair. Some Scrup'l did quick work with a can of 7955 Silver Metalic Rust-Oleum.
OK... it's looking more like the usual Whatziss you host around here, John! Much less like the previous picture, which was very phallic. This one, on the other hand... well, let's just say it has too many sharp edges.
Is it some kind of WP incendiary grenade?
Good thing I didn't guess M407A1: (scroll down to "HE Practice Grenades- $350). Could you confirm it's a 40mm x 46SR vice a 40mm x 53SR? Cheers JMH
I was wondering if someone was going to find that page... and no I can't. I don't own this particular one.