First of all, this is not completely MY idea. I must thank PP for thinking the idea up, but I noticed he has put it on the back burner and it has indeed intrigued me.

I have always had a mind for mechanical things...and that's what I will be going to college for (Mech. Engineering). So I felt this project would be kind of a cool thing to do.

After thinking about this project for a little while I found a relatively easy way to make this work.

The Magazine
This is probably the easiest part of this entire project. This will be a metal magazine with a simple spring loaded magazine design. It will use a spiral inwards to allow maximum ammo capacity. There will be a large spring coming out of the center of the spiral with a follower with an inward convex on the end of the spring. The shells will be spring loaded by this mechanism. At the end of the spiral (or the top of the magazine where the ammunition will leave the magazine and enter the chamber) there will be a hole for a pin to be inserted. When loading the magazine the user can push the shells in, then insert the pin and remove any excess shells (should only be 2-3) from the magazine. If desired (for maximum ammo capacity) the user can keep those few shells in, insert the magazine, and remove the pin. Now all of the shells will be spring loaded and as long as the magazine is kept in the gun there will be no problems.

The Trigger
This is the most complicated part of the build! The trigger will be what I am calling a dual stage trigger. Since I will be using gas shells (like the madbull shells) which are fired with a pin pushing into the end of the shell to release the gas and the BBs. But that's the second stage of the trigger. The first will be a lock that goes around the end of the shell when it's in the chamber, this way when it is pushed forward it is not just ejected by the spring loaded ejector. When the trigger is pulled the "lock" will go around the shell in the chamber, and push it forward into it's firing position, as you complete the trigger pull the pin will then come out of the center of the "lock" and fire the shell. When the trigger is released the shell will stay in place while the firing pin, and the lock retract back to their resting position and the shell will then be ejected because the spring in the ejector can be released which will clear the chamber and allow for another round to be pushed forward.

I have been thinking of making this gun fully automatic and using a small gearbox to do this process...I am not sure what I will do about this yet though.

The Chamber
This is one of the more difficult parts of this build...it requires some finely crafted parts and I am going to assume some tuning to get it working perfectly. The basic concept it somewhat simple however. Once the magazine is inserted, a shell will be lifted into the chamber, where the shell will sit. Once the trigger is pulled the dual stage trigger (see Trigger above) will engage. The shell lock will come out first of course and surround the end of the shell. It will push the shell past a spring loaded shell ejector and this will then push it into it's final position. Once the trigger is released the shell lock will retract and will no longer hold the shell and the shell ejector will eject the shell out the ejection port.

Shell Ejector
This is a simple mechanism actually. It is a going to be a strong spring loaded mechanism (like most parts of this build!) with a hinge on the end of it closest to magazine. This way, the shell will be able to simply pass over the ejector plate when it is pushed forward by the trigger lock and compress the spring. Then when the lock retracts the ejector plate will be able to eject the shell from the chamber. This enables the magazine to put another shell into the chamber and the trigger to push it forward to be fired, thus repeating the entire process!


I know this is all very confusing to read most likely, please post if you would like clarification on any parts of it, I will also try to post some pictures of some drawings I've made.

Any input is welcome, thanks!

Sounds cool. Are you using CNC Aluminum? When are you going to start?

CNC Aluminum? No sir, that's too expensive for me! I'll be custom fabricating the body, and using parts from some of the things I have lying around. I'm going to start pretty soon, just trying to decide if I want to make it an electrical trigger, or completely mechanical.

Best of luck, bro. Glad to see I'm not the only one that had interest in this idea. Even though I haven't been able to do much with it, hopefully you can.

PP

Since you seem to have an idea of what you want to do I just wanted to donate my 2 cents here
1. I'm very interested to see how this goes, please be sure to regularly update.
2. You should go with shells that are more disposable, or at least consider the Maruzen system where the shell is only, well, a shell. This allows for gas to be stored in a separate area like the pistol grip in the Maruzen M1100 Revision. You might say, with a limited amount of gas in the grip shot to shot consistency may suffer, but the same with individually loaded shells. Plus, the Maruzen shells are actually in stock (too lazy to do a real search). This allows your action to be much more simplified (no requirement of a firing pin here, just a slightly modified TM M9 nozzle).

Hope this works, I'm very interested in the idea. Keep us updated please :D

Leaf

Thanks for the kind words guys, I will update this as I build...

I may use the maruzen shells because well...they're simpler. But also because my gun is going out to polarstar this next week to get a fusion engine ! This also means I will have an air tank and HPA rig so I could just run the gun to an HPA rig. I will keep you guys posted!

Nice idea with the HPA setup.
Now if you can, I would just replicate/use the internals of a scrapped grenade launcher for a base of your cylinder/magazine (to clarify, the clock spring and trigger mech.). That way, you can do a prototype and instead of a pin you would need to just have a gas valve like any GBB. That is the only I challenge I see other than fabrication and fitting the parts together.

I can't wait for people to pick up the shells LOL
I don't remember how the real thing works.
But maybe you can try to make the magazine to unload like revolvers.
So instead of picking up each shell, you can just dump them into your dump pouch.

But of course, you can just attach a bag to catch the shells or use it as a fun gun instead of fielding it.

Best of Luck.
If you can make one that actually work, I'd order one from you lol



If I can afford it lol

From what I've seen, and I will certainly not claim to be an expert on the operation of the real firearm, is that it has a load port on the right side of the drum mag, next to the receiver. From what I've been able to see, loading operation is done with an individual shell loaded into the port and the drum is then manually rotated. Depending on the model (Protecta, Striker 12, ect...) that step is slightly different. When firing there is a small hinged piece of metal that can cover the load port after loading can stay shut, so that when fired, the ejection does not occur and remains in the drum. In some videos, you'll notice that no shell are ejected after rotation of the drum. I even saw a video where someone manually ejected the shells after firing, so, picking shells should not be much of a problem. That is if you conserve your shots, somehow, with a streetsweeper.

Good Luck, but I would avoid the gas holding shells

LOL STRYKER WITH A STRIKER

Really liking the HPA idea. Also as for your trigger dilemma I say go with the mechanical. Not sure how much of an artist you are by it might be a good idea to draw up a good diagram/plan before starting. Helps a lot!

Three things popped into my mind while reading your description: Expensive, time consuming, and awesome.

Be aware that because you have a complex system to fabricate from scratch, you are in for a veritable hailstorm of problems and a heckuva lot of time.

That said; go for it! It will be worth the effort!


A while back, I used paper cylinders with BBs inside muzzle loaded into a $10 paintball gun from walmart to fill essentially the same role as a GL and a bunch of shower shells. It was nice because I could carry lots of shells and not worry about charging them or putting them somewhere after used, but they worked almost as well as a commercial shower shell. You could use such shells in some manner of roided up paintball gun, and they do not have to be ejected, as the cylinder is fired with the bbs.

The only problem is you have to make and load the little paper shells by hand.

I've been looking around for a shotgun, haven't found one yet to use as a donor. If anybody finds a gas shotgun, either gas in shell or gas in gun...please send me a PM! Thanks!

Maybe you find this useful:
http://www.icsbb.com/web_e/html/02_product...=27&num=628