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Double Barreled Multishot Shotgun Concept

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Double Barreled Multishot Shotgun Concept

Unread postAuthor: Zippster » Tue Aug 05, 2008 8:12 pm

Please note - I had this entire thing all typed out, and freakin explorer (this comp's stuck with it) crashed and lost the whole thing. So if I miss any details, that's why.

- - - - - - - - - - - - - - - - - - - - - - -


There are 3 cannons I like to build: spud relocators, BBMG's, and airsoft shotguns. Of the 3 shotguns are the farthest behind on the tech tree - but not for long.

I plan on combining koolaidman's double barrel idea with B the B's repeater and add my own ideas to create the selective double break barreled multishot airsoft shotgun from hell. The concept is to create a shell-loading shotty with dual barrels that fire indepently of each other, and use the repeater aspect to fire both barrels in turn and reload a few times on a single tank.


Concept Pic (not to scale, and certainly not fully-detailed)
Image

Yes I have mad paint skills 8) :roll:

However before I go out and spend anything (I'm a real tightwad) there are a few issues I need to work out:


- 1. - Selective Shooting (ie. firing the barrels independently)
This is the biggest thorn in my side for this project. The trick is to get a slick selecter mechanism without a ludicrous ammount of valves and barrels that are 5 inches apart. The most obvious solution would be to have a ball valve for each barrel to turn it on or off, but that is a last resort. The thing is - I dont know how else to do it. about the barrel seperation, I figure a manifold would do, but I dont know which one/what kind to use. Any thoughts on that would be helpful.


- 2. - Multiple Shots (on one tank)
Seeing as it takes a ridiculously small ammount of air to fire one of these shotguns airsoft-safe (I got one to work off of a foot of 1/2" pvc for a chamber and a ridiculously loose ball valve I could snap my fingers to open) and I'm using a QEV instead, it has potential for a lot of shots. The problem, however, lies in resealing the QEV and piloting it without too much air loss. Having never owned a QEV before, I draw my experience from a modded sprinkler that'll honk for a good 5 seconds after fired when left connected to the air source - and thats not good. I hope to god that a QEV will perform better, and anyone with knowledge on the matter would be obliged to speak up now. As for piloting the thing, I figure that a simple tap on a blowgun would suffice, but again this is where my experience hits a brickwall.


Those key issues notwithstanding, I feel pretty good about this build, but any advice as to buying parts or some problem I failed to address would help immensely.
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Unread postAuthor: starman » Tue Aug 05, 2008 8:51 pm

If you pick the link at Imageshack labeled "Direct" and put the IMG tags around it, it will resize and display much nicer.

I would say get to work on something and give us some progress details. It looks like you have given your project a lot of thought already.
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Unread postAuthor: Sticky_Tape » Tue Aug 05, 2008 9:30 pm

so how do you pilot the gun it looks kinda weird hintity hint hint.
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Unread postAuthor: Zippster » Tue Aug 05, 2008 10:10 pm

Well the paint diagram isn't supposed to look like the gun, just show how it works. Think a circuit diagram (if there's no special name for them). That and it did resize properly, its just small (click on the link).

I'm using a blowgun mounted on a grip not pictured, so I've got that part figured out.

EDIT: Just ordered a 3/4" QEV off of McMaster, so I'll see how that works for me
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Unread postAuthor: koolaidman » Tue Aug 05, 2008 11:03 pm

wow, this is a great idea, good luck. I didnt have the balls to try and make mine shoot separately. I wasnt really sure thow to accomplish this. Id think either a 3 way ball valve, or making your own flap to select the barrel. Will it be break action (like mine?)I dont really understand the need for a reg for multishots when youll only need 2. unless you wanted to make a vierling shotgun with 4 barrels!
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Unread postAuthor: psycix » Wed Aug 06, 2008 11:37 am

1- 3-way ballvalve (L-type) or some piston system.
2- Choke/obstruct air source or make some mechanical trigger system that makes sure air source is only open on full trigger release.
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Unread postAuthor: Zippster » Wed Aug 06, 2008 11:55 am

The regulator should serve a double purpose. Firstly it should help me get more shots out of the tank. Hopefully it'll be enough to get a few reloads out of the gun, which yes will be break action. Also it should restrict the airflow as to minimize waste upon piloting.

For the fire selection a 3 way ball valve would be great, but I wouldnt know where to get one that is in a viable configuration. All the ones I could find are shaped like a T, and would add too much deadspace. I was going to use the 1" to 4x1/2" distributor off of flexPVC and just plug the bottom 2 in such a way to get rid of as much deadspace as possible. I have absolutely no confidence with making my homemade contraptions seal properly (still cant seal a coaxial), so I want to avoid anything custom as much as I can, but if you can explain this flap selector of yours a bit more that'd help.
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Unread postAuthor: Carlman » Wed Aug 06, 2008 1:48 pm

you can get a Y shaped thing for turning an outside tap into two lines with two ball valves on each spigot. Mod one of then and you'll be laughing!
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Unread postAuthor: Zippster » Thu Aug 07, 2008 8:32 pm

On a completely different note:

Is there any real trick to getting threaded parts to seal properly other than using a s***load of teflon and tightening it halfway to hell? I've gotten the majority of the parts to seal, and the rest to greatly reduce their leakage (the good o'l submerge 'em test) to a barely noticable stream of mini-bubbles, but with more than one of these parts leaking at 20 PSI test pressure, it'll drain the 45 cubic inch chamber pretty fast at 100 PSI.
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Unread postAuthor: trollhameran » Fri Aug 08, 2008 1:09 am

make sure all the parts that could leak, or move under pressure have teflon tape around them, I had loads of leaks on my latest gun, but tape on all the threads and around the olives on the pipe fixed it up nicely.
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Unread postAuthor: CasinoVanart » Fri Aug 08, 2008 1:59 am

Zippster wrote:On a completely different note:

Is there any real trick to getting threaded parts to seal properly other than using a s***load of teflon and tightening it halfway to hell? I've gotten the majority of the parts to seal, and the rest to greatly reduce their leakage (the good o'l submerge 'em test) to a barely noticable stream of mini-bubbles, but with more than one of these parts leaking at 20 PSI test pressure, it'll drain the 45 cubic inch chamber pretty fast at 100 PSI.


You could try and use loctite Hydraulic sealant, i used it on a triple chamber co-ax and it seems to be doing a sterling job, i haven't tried to unscrew the parts yet so i don't know how "servicable" it would be, i have been told that you can undo the threads after applying though.
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Unread postAuthor: Zippster » Fri Aug 08, 2008 5:54 pm

Well, the QEV just came in from McMaster earlier today, and so far its extremely disappointing. It sucks. I can outdo this thing with a 1/2" ball valve. Im sure I got the orientation right because it does fire and all, its just that half the air goes out of the pilot. On the gun setup it didnt work at all, it just dumped the resevior through the blowgun. I only got it to work with a 1/2" BV piloting it on a test rig without the main resevior, and most of it whent right through the BV. Just the overall construction of the thing makes it seem much much cheaper than the $20 I payed for it (yes it is the McMaster part #6646K23 ).

Am I blind, or is there something wrong here?
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