8 replies to this topic

[DougStump]

Q the James Bond music.
🎶You only live twice, or so it seems 🎶

This is only the 3rd Gyrojet that I've seen in the flesh and it followed me home today. And it came with 10 rockets! It's one of the earlier models in 13mm, after the Gun Control Act of 1968 they switched to 12mm and rifled the barrel.

When you pull the trigger, the hammer (shown uncocked) pivots up and whacks the nose of the rocket, forcing it back into the firing pin, detonating a standard small pistol primer to light the solid grain of propellant. The hammer restrains the rocket until sufficient thrust is developed to recock it. The rocket is now free to go on it's merry way, the exhaust nozzles in the rear are angled to give it spin (some rockets have two nozzles, others have four). With the firing chamber now empty, the magazine shoves a fresh rocket up into position. Note that the slide does not move when firing! You only pull it back to load the built in magazine

As you might imagine, the rocket starts out fairly slow and continues accelerating for 10 to 15 yards or thereabouts. If I do decide to fire it, I'll definitely have the LabRadar chronograph set up! I do believe that reloading for it is somewhere in the impossible range.

An interesting idea that was just too far ahead of it's time.

 

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Edited by DougStump, 07 April 2021 - 09:38 AM.

[Paladin601]

That is neat, guess it is hard to find new Rockets?

[DougStump]

No, not hard at all. It's damn near impossible!

[Mike Hammer]

Those guns are so cool. It's a shame you can't really shoot them because of the scarcity of the ammo. I wonder how difficult it would be to try to manufacture new ammo for it. Obviously the demand is just not there for a large scale operation of that sort. Really a unique but kind of wild idea those were.

[Burns556]

When I was a kid I thought this was about the coolest gun out there. Back then ammo could be found, think it was around $12/shot, never ended up getting one.

 

Great article mentioning its use in Vietnam.

https://www.american...ms-sog-warriors

[DougStump]

The total pistol production was somewhere around 2,500, with a much smaller number of carbines. So there really isn't much of a market to justify new rockets. But... Just as a brain exercise.

The outer casing (brass plated steel) could be drawn or CNC machined. I don't see why they couldn't be 3D printed on a printer capable of high strength metal. A cost analysis would be in order.

The bases were machined and the 2 or 4 nozzles hand drilled with a jig. This probably explains the inconsistent accuracy. The last rockets produced used sintered bases (mold compressed metal powder, then heat fused) and were allegedly more consistent. Standard small pistol primers were crimped in. Again, modern CNC or metal 3D printing should work well.

The biggest stumbling block is the propellant. The originals used a single grain of nitrocellulose, allegedly the fuel rods for 3.5" bazooka rockets. Cut into sections, then turned on a lathe (yes!) to the proper size and shape. A center hole bored, and a ignition booster (either a thread of guncotton or a strip of flash paper) inserted in the hole so the propellant burned from the inside out. Yikes! As long as the propellant could be safely machined, CNC would be the way to go and would be much more consistent than machined by hand. I have read a couple of articles on 3D printing explosive shapes. If there was a suitable propellant that could be extruded, this might be the best option.

It would be an interesting experiment, but the start-up cost would be very high.

[JimB]

ammo is not too hard to find, its just insanely expensive, often well over a hundred dollars a round today.

 

MANY Moons ago it was dumped rather cheap when MBA folded

 

There is much myth regarding both the guns and their ammo

 

1st off it was ATF that shut down production

deal was that it was a DD

I have owned both the original 13mm and the later 12mm

never seen a 12mm with a rifled bore

further, spin stabilization occurs via canted venturis

rifling would degrade any potential accuracy.  The barrel is no more than a launching tube

ATF let rifling slide as the "barrel" was near zero pressure bearing

 

I was an indulged kid

ended up with a 13mm with close to 500 rounds in the early part of the 70s

shot nearly every round I had

corresponded with MBA engineers as well.  Still have some MBA paperwork filed away

 

So guys understand MBA specialized in what was to be the next generation of Combat Weapons

While the Gyrojet is now a cult fan boi thing there were other developments some are very well known and widely used today

 

MBA developed the first bean bag rounds

started as a thing to sell to air marshals as the were designed to not penetrate the pressure hull of a commercial airline

From there they developed 37mm bean bags as well as riot baton launchers

thing was those plastic batons were rifled which ATF decided made them DDs

there was a CO2 variant as well but MBA dropped the whole line

Steve McQueen uses one in Bounty Hunter

[Kilroy]

Really cool.

[johnsonlmg41]

One of those is on my long list.  Would love to shoot one.  Seen a lot for sale over the years, but they've all gone for bigger money than I want to put in.