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Rotary Breech?

Would it be feasible?

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#1 Ronnies07

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Posted 15 May 2006 - 11:22 AM

I was wondering if a rotary breach mechinism would be at all fiesable for motorized rifles,
such as the one featured in the HK-G11

The G11 has a loading and ejecting system like this:

Posted Image

So i was wondering if this would be usefull in a mechinized or manually operated fashion such as this:

Posted Image

First the shell with the dart is loaded.

Seccond the chamber rotates so the dart is placed horizontally, the gun fires the dart.

Then the chamber rotates further to eject the shell out of a hole in the bottom of the gun.

And the chamber rotates back into its inital state to fire again.

So would it work? Or be usefull at all?
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#2 Carbon

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Posted 15 May 2006 - 11:42 AM

Interesting idea! The biggest problem is that you'd need a second valve in between your air tank and your breech. You'd never get your breech rotated quickly enough, and you'd end up losing all your air before you were in firing position. The cool thing is that you could potentially use a tube-style magazine, as opposed to a stacked mag.

So perhaps this....keep your breech idea, and place another valve in between your breech and airtank, but make it a solenoid for quick air release.
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#3 murakumo32

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Posted 15 May 2006 - 12:33 PM

I like the idea. You could potentially make a clip that loads sideways like the P90. But as Carbon said, you need a second valve. Anyone have any thoughts to optimized this?
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#4 Forsaken angel24

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Posted 15 May 2006 - 12:45 PM

Cool find! I think it would be neat to work with a tube clip system but it would seem that we would have this goofy rod sticking out of our gun as a magazine. Anyone know what kind of parts we would need to make this?
I mean like the rotating chamber specifically.
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#5 Ronnies07

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Posted 15 May 2006 - 01:23 PM

Well my mockup drawing doesnt show the valve, As I included the "Airtank" as more of a refrence point to show the workings of the breach, but yes, there would be a valve there.

But it is enlightening to see such positive replys to my first post.

But as materials go, I would imagine that if you insert a piece of 1 inch PVC or CPVC through a larger (lets say 3") all the way through the side and glue, that would be sufficiant.

Edited by Ronnies07, 15 May 2006 - 01:32 PM.

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#6 Megothitinheadbydart

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Posted 15 May 2006 - 02:23 PM

Use a ball valve for the chamber, and set up a system of solenoid valves and an electric motor to make the thing full/semi auto. You would really only need one little solenoid, since the ball valve would work as the actual "firing valve".The only proble would be finding a gear motor strong eough to turn the ball valve quickly enough to allow a decent rate of fire.
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#7 Ronnies07

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Posted 15 May 2006 - 03:06 PM

Why use a ball valve? I would think a butterfly might be a better option
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#8 Megothitinheadbydart

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Posted 15 May 2006 - 03:35 PM

A butterfly valve would require much more precision in the design, since it must be entirely closed before the valve can open; but, if you used a ball valve and made the inside of the "ball" the chamber, you could use the ball valve as the only valve, or if you wanted a semi-auto or full-auto nerf gun, as one of two valves. Plus, from what I see on mcmaster-carr a butterfly valve would cost at least 5-10 times as much as a ball valve.
However, if you were going to use a butterfly valve anyways, you might as well make your own rotating piece for the nerf gun. That way you would still need two valves in addition to the rotating chamber, but it could have much less friction like a butterfly valve and cost a lot less than any other choices.
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#9 Shotty Master

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Posted 15 May 2006 - 05:46 PM

I don't think a butterfly valve or a ball valve would work for the desired function. The ball valve would work if you fired super small darts, but what fun is that? Another problem with the ball valve is the dart would most likely fall out the other side. I like the concept though, i really like it. Verry innovative. Hopefully with the engineers we have on here and the other technical minds we have, we can come up with a fesable solution.
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#10 SKIZ

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Posted 15 May 2006 - 06:17 PM

You could hook the rotating device on small 12volt motor that periodically stops at each point. (the shell load, the shot taken and the ejection of the shell) You could then use contancts on the rotating device to fire the solonoid. I.e. when the shell is in position to fire contacts will be aligned and ready to fire. To allow for better but slightly slower ejection you could always make one of the opening of the rotating device smaller. That means that the dart will only have one way to travel and theres no chance of it falling out the other side. The bad side of this though is that the dart would basically have to do a 360 before it could be fired again. Basically this allows for automatic fire.


NOTE: I will have a picture for you later today, as i no that what i said would be hard to understand.
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#11 ompa

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Posted 15 May 2006 - 06:34 PM

Welcome to NH Ronnies! Nice to see someone with some great ideas posting about them right away. If you have any question about anything, feel free to PM me.

By the way, guys, you don't need a huge clip sticking out one side. The P90 is an excellent example. Just rotate the diagram he has.

I'd be most worried about getting a proper seal. I suppose foam craft sheet would get you a sufficient seal, but I think the hardest part will be, as odd as it sounds, getting any sort of back-forth motion to turn into a turn-the-turret motion. I suppose you could make one position the resting position, and have a spring return it to its resting position after you prime it, which could be accomplished by a string just pulling on the thing itself.

My only gripe with it is that it almost has to use shells. I'm not very fond of shells, at it results in increased loading time, expenses, etc. However, the use of shells DOES allow for a better seal to be made, which would be required in this case due to the fact that otherwise you have a huge open compartment that's open to the air chamber.

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#12 Carbon

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Posted 15 May 2006 - 06:47 PM

My only gripe with it is that it almost has to use shells. I'm not very fond of shells, at it results in increased loading time, expenses, etc. However, the use of shells DOES allow for a better seal to be made, which would be required in this case due to the fact that otherwise you have a huge open compartment that's open to the air chamber.


Not necessarily. We've seen before that large open chambers don't necessarily kill range if there's enough air present; the RSCB clip and my hopper clip are two examples of that. It really wouldn't matter if the dart was sitting loose inside of the pipe, just so long as there was smooth pipe channeling it forward.
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#13 Ronnies07

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Posted 15 May 2006 - 09:44 PM

A butterfly valve would require much more precision in the design, since it must be entirely closed before the valve can open; but, if you used a ball valve and made the inside of the "ball" the chamber, you could use the ball valve as the only valve, or if you wanted a semi-auto or full-auto nerf gun, as one of two valves. Plus, from what I see on mcmaster-carr a butterfly valve would cost at least 5-10 times as much as a ball valve.
However, if you were going to use a butterfly valve anyways, you might as well make your own rotating piece for the nerf gun. That way you would still need two valves in addition to the rotating chamber, but it could have much less friction like a butterfly valve and cost a lot less than any other choices.


True but as others were saying, wouldant all the air rush out of the gun before the breach can close, (or am i not understanding what you are saying)

Also oompa, you may not need shells for anything but the mag, resulting in a powerclip style magizene, but it would add more complexity to the gun instead of a shelled mag

Also carbon, The berral being much bigger then the dart was a mistake on my part drawing it, the dart should loosly fit but not too loose as shown in the picture.

I just drew that to have an example of the breach workings, but that is by no means a full plan for a gun

Also i was thinking that if you added a small O-Ring slider that was able to slide in the breach, you would be able to fire two darts every cycle of the breach, so once the new shell is loaded, the spent shell is pushed out and the Oring to keep it from falling out prematurealy. its kinda hard to describe without pics but hopefully I can post some tommarow.

Edited by Ronnies07, 15 May 2006 - 09:57 PM.

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#14 Carbon

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Posted 15 May 2006 - 10:26 PM

Also carbon, The berral being much bigger then the dart was a mistake on my part drawing it, the dart should loosly fit but not too loose as shown in the picture.

I was actually talking about the other way around; where the chamber would be loose around the dart, but the barrel would be close fitting. The dart could just fall into the breech (no need for shells) and then get shot forward into the barrel.
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#15 CaptainSlug

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Posted 16 May 2006 - 04:55 AM

There's no need to motorize this since it doesn't need to rotate all of the way around to function. It could just tilt back-and-forth 90-degrees between the first two steps in the image.

If you put a cam on the rotating breech it could mechanically trigger the firing valve for you. And then find a way to link the rotation to a trigger and you'll have a very effective and simple semi-automatic system.

If you need me to I could work up a design in CAD.

Edited by CaptainSlug, 16 May 2006 - 05:02 AM.

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#16 The Inventor Guy

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Posted 16 May 2006 - 05:00 AM

I like the idea. You could potentially make a clip that loads sideways like the P90. But as Carbon said, you need a second valve. Anyone have any thoughts to optimized this?

Yeah, I was thinking something similar, more along the lines of the HK G11 Assault Rifle. The rifle has a turn table in it to chamber and eject shells. Quite interesting. Though in the G11 design, it takes and ejects a cartridge in 1/2 turn as opposed to the full turn of this design.\
I see this design as very feasible. Good work.

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#17 davidbowie

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Posted 16 May 2006 - 08:38 AM

I don't really like the design all that much, but I can see it going somewhere. Of course, there's still the problem of needing very precise dart length.

Here's what I'm thinking:

Lever action. Attach a lever to the valve handle, mounted so that it would hit the handle stops with the ball opening (in front) just above the barrel. Drill a hole in the casing to line up with the opened breech. Attach a sprung lateral mag, with a gentle bend to line up with the ball when the breech is opened. The mag would be on top of the barrel. Dart scrunching would still be a problem, but I can still see this working. Perhaps somebody will be inspired.
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#18 Ronnies07

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Posted 16 May 2006 - 10:31 AM

I like the idea. You could potentially make a clip that loads sideways like the P90. But as Carbon said, you need a second valve. Anyone have any thoughts to optimized this?

Yeah, I was thinking something similar, more along the lines of the HK G11 Assault Rifle. The rifle has a turn table in it to chamber and eject shells. Quite interesting. Though in the G11 design, it takes and ejects a cartridge in 1/2 turn as opposed to the full turn of this design.\
I see this design as very feasible. Good work.

-Tidge.


Yes I did bais the design on the HKG11 as stated in my first post, but the links are broke now for some reason.

Edited by Ronnies07, 16 May 2006 - 10:31 AM.

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#19 Alexlebrit

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Posted 17 May 2006 - 02:00 PM

I've actually built one of these, but using BB's not darts (shhhhhh) and unregulated CO2. For spehrical hard ammunition it works great, the rotatling breech also acts as your firing valve as your projectile can only be fired when the breech is fully open. Prior to that it's blocked from moving and so no air escapes. As a BB Machine gun it's very effecient, and of course you can adjust the rate of fire with a speed controller.

HOWEVER. I'm not using any form of cartridge so don't need to eject anything, I'm using small, round hard ammo. I'm not totally certain you could get this to work simply with a cartridge as there's a very strong risk of jamming on the loading or ejection cycles. Don't forget even the HK is caseless.
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