370 replies to this topic

[SHADOW HUNTER ALPHA]

Quite the scrounger, are we not, LastManAlive? I have not been able to start my gun yet, so I unfortunately don't have any pictures. I might be able to do something over this Thanksgiving break or mybe Christmas break, but I'll need a lot of free time. (Freshman year in high school is always a pain in the ass, especially the workload.)

I was also kind of waiting to see if I could build some scale models. If you've ever seen the show Mythbusters, then you know that it is a better idea to build a scale working replica of the final product rather than jumping into the pool without checking for any water first. As for hearing about it, you should keep checking this forum. Even if I can't get anything done soon, the discussions here have all been helpful and detailed, thanks mainly to the major contributors in this post. Should I start anything, I'll keep you all informed.

[Flaming Hilt]

You should try Junior year.


Yea, I'm definitely not going to be able to start mine soon, but I think we're all in similar boats. I'm going to finish modding my 3k and finish two homemades I've started before beginning my shotty. Mostly the 3k/2 homemades are for experience ('cause just talking about this thing makes my head spin ), but also because I've started these three things and don't want to have four projects going at once.

So yea, I think we're all going to build (or attempt to build) our own variations of the same concept, it's just a question of when. Those of you spectators had better have a lot of patience.

[Commonly Hunted]

I'm also designing a shotgun and I've got a design that is simple and it looks like it will work so I'm going to try to make a prototype this weekend. If it works I'll post the design (I haven't even had time to make that) with any necessary changes. I don't have the mag spring so I'm gonna use rubber bands until I find one.

I'll update later.

[SHADOW HUNTER ALPHA]

Flaming Hilt was right when he said to be patient. However, I think I speak for all of the contributors when I say that any models, scale-built or otherwise, are greatly anticipated and appreciated. I might have time to begin a carrier/carrier dog model, or start a removeable receiver this week, but I wouldn't put any money on that.

[Meaker VI]

It occured to me last night that with real shotguns, it doesn't matter how you put the shell in the chamber (as long as it's not backwords), it'll pretty much always return to the proper orientation before being rammed into the barrel. I thought that that could be possible by having the carrier force the shell against the top of the chamber, which is something we could work with.

[Commonly Hunted]

Isn't that what you originally planned to do? If not, then could you help me understand what you are saying?

[Flaming Hilt]

I think what he's saying is that the bolt will always straighten the shell. Thus, we don't have to have the carrier get the shell PERFECTLY into position. Just as long as it orients it in a way that the bolt can grab it.

Which yes, does change some things.

[Commonly Hunted]

Oh, okay. That was what I used in my design. But I still don't have a design finished to show you guys. Maybe I'll make a quick design on paint when I get home. I'm at school right now and the school's computers don't even have paint. They run on some Linux based Operating System called Konqueror. I hate it.

I am also half done with the 3D model of my design made in AutoCAD 2006.

Anyways, in my design, my carrier is just a ramp. There is a little tab (like in the Buzz Bee Double Shot) a little bit ahead of the carrier but connected to the bolt that keeps the shells from popping out of the magazine. The bolt and plunger will be the same as in Ompa's version of the SCAR-N. But the bolt will have to be changed to allow the chambering and ejection of shells. The barrel will be over the magazine just like in a real pump-action shotgun. It will be made with 1/2" PVC, 3/4" thin-walled PVC (my Lowe's has every size with thin- and thick-walls), 1" thin-walled PVC, and e-tape. Then, if you want a different size barrel (smaller than 1/2" PVC), you just nest CPVC or brass into the 1/2"PVC. I will be using CPVC for the prototype, brass if I can get it by then, but the design will show brass. The chamber will be very similar to the FAR's (SCAR's if I use brass) but will be a size smaller because the shells will only be as big as 1/2" PVC. The pump action will probably be a mix of the SCAR-N's pump-action and the NTS's slide-action (only the music wires). Finally, the stock will be made out of pipes and shaped like the stock from this rifle:

My sketches already look just like this gun but I haven't been able to scan them until just this past weekend and I've decided not to scan them (I hate messy lines and paper lines look dark on scanners). I will just make these on paint and CAD and then post the pics.

I don't see any problems with the designs except that it come out kind of long. This will be because the stock will not be able to house any of the internals of the gun and the receiver will have to cover the plunger, bolt, and barrel chamber.

Sorry if you can't understand this but I will get pics up soon.

Edited by Commonly Hunted, 29 November 2006 - 05:13 PM.

[SHADOW HUNTER ALPHA]

To shorten the gun, I was going to borrow another design from Boltsniper and use the stock's horizontal tube to house the plunger and spring. This way the gun can still be manageable in size, but not suffer any range or reliability issues. I plan to make the gun about 76cm (~30 in.) long, but I may need to lengthen it a little to make room for more shells in the magazine. Right now I can fit about 5 shells with that lenght, and I was hoping for 6-8 to make it more practical.

[Meaker VI]

Yeah, Flaming Hilt hit it on the head with what I was trying to say. I was running late after waking up and wanted to write that down somewhere before I left (I had thought of it while sleeping), and was already checking my email and stuff. But yes, the idea is this: the barrel is inside the chamber which has a notch cut out of it approximately the leingth of the shell, and then the sides of the chamber-carrier area would be the same width as the shells and thus the carrier would always righten the shells when they loaded. I saw that work on a real-steel shotty while my friends and I were shooting last weekend and it had just hit me.

Then, all that would need to be dealt with is the length of the bolt (and possibly a way for it to interface with the dart in the chamber), the stroke of the plunger, and the way the carrier and plunger interface. I was also concerned with how to keep the shells in the loading tube, but that can be worked out later; right now I've been in the Architecture stuidio something like 14 hours.

[LastManAlive]

Quite the scrounger, are we not, LastManAlive? I have not been able to start my gun yet, so I unfortunately don't have any pictures. I might be able to do something over this Thanksgiving break or mybe Christmas break, but I'll need a lot of free time. (Freshman year in high school is always a pain in the ass, especially the workload.)

I was also kind of waiting to see if I could build some scale models. If you've ever seen the show Mythbusters, then you know that it is a better idea to build a scale working replica of the final product rather than jumping into the pool without checking for any water first. As for hearing about it, you should keep checking this forum. Even if I can't get anything done soon, the discussions here have all been helpful and detailed, thanks mainly to the major contributors in this post. Should I start anything, I'll keep you all informed.

Flaming Hilts post alone explains my predicament.

I have Trig and CADD (may not seem like much) on top of work, daily activities, and my own free time ussually consisting of an hour to an hour and a half after I finish my homework or at least put a major dent in it. And an hour or so is meerly enough to get my thoughts together and start this. I wouldn't be able to get much accomplished without being to continue something the next day for yet another hour. I would have to get on pace again and all that. I will wait until summer for work to come to a stand still or just quit and get a part time somewhere.

[SHADOW HUNTER ALPHA]

I was also going to wait until around the beginning of summer to assemble this thing (for the same reasons you are). That doesn't mean that I won't try to make models or parts until then, but I wanted to use my spare time now to get the design as close to perfect as possible before I get down to the actual fabrication and whatnot. With you all contributing, it shouldn't be difficult to work out an effective system.

Edited by SHADOW HUNTER ALPHA, 30 November 2006 - 09:16 PM.

[Ronster]

I found some gears!

So, as soon as I have free time, that prototype'll be first on my list!

[SHADOW HUNTER ALPHA]

Speaking of prototypes, I made a crude model of the shell ejection system. It is a little bulky and long, but it's just in the design phase.



The tip is a nail, the body is a cut-down tube from a Bic pen (with hole cut in black end cap), the two springs are from some spare pens, and the springs are threaded onto a second nail. The heads of the nails are touching, and the blue cap is the cut-down base from a blue wall anchor (like the kind used for nails) with the side tabs, base rim, and fluted tip removed.

Overall, the ejector has enough power to put small holes in pizza boxes when fully depressed. Suggestions or comments, anyone?

P.S.: Ronster, I hope to see a successful model of the carrier so we can actually prove the concept in scale for a nerf gun.

Edited by SHADOW HUNTER ALPHA, 01 December 2006 - 05:57 PM.

[Meaker VI]

Alrighty, now that that architecture project is done and I've slept a few days...

I have a fairly complete design in Sketchup, and I'll work on posting pictures later tonight. Right now I'm concerned with trying to finalize the deisgn though; I'm not sure what the exact numbers are on any of the PVC or CPVC diameters are, although I've downloaded Boltsniper's numbers sheet I'd like to know for sure that mine are the same. Once I get real numbers I can take the design out of the conceptual phase and actually design it for construction. If someone could give me the diameter of a stock tagger-dart, that'd be helpful, since I plan to use those (I don't have anything on hand while at school). I know that they fit much better than any other type of dart in what I think was 1/2" PVC, barrel-wise anyway.

Roight... Got the picts... The black is the barrel assembly, the yellow is the mag tube and plug (and the sling that holds the barrel and tube togeather), the blue is the chamber, red is the plunger, grey are shells, and either green or orange are either pump or carrier (I'm color blind red/green, the red is far enough off to be easy but the orange and green are blended for me)

This image is the initial priming. With the pump in the forward position the lock on the mag tube is down, and shells are free to slide out under power of the magtube spring. They slide into the chamber/carrier assembly. My issue here is getting the mag tube locked again after 1 shell comes out, I'd appreciate comments or designs to fix it. Presently, that yellow rod that is bent is the lock, and as you can see it should work except that when the pump is forward it is permently down and there is no easy redesign to fix it. A completly new part would be nessecary.

This image shows the pump moving back, taking away the plunger/bolt assembly (which isn't fully developed, but I'm not very worried about. Plenty of these assemblies have been developed and all I need is one that forces the shell forward a little-hence the prong on the front of the bolt), and the notch on the pump's connecting rod engaging the carrier and forcing the shell down into position. In this motion, the shells need to be locked in place (as stated above), the bolt needs to prime the plunger, and the carrier should be held down untill the bolt has engaged the shell.

This image is the return stroke, where the bolt engages the shell, the carrier releases, and the magtube re-opens. A new shell slides into partial position on the carrier, which is something I nearly overlooked in my design that needs to be addressed: The mag tube should have a bevel to it to allow for this motion. The gun will now be primed and ready to fire, after firing the re-charging motion will need to expel the spent shell. This is something I have not shown, but I was planning to have a spring-loaded door that the shell was forced out of by the next shell and the carrier. It should work since the next shell won't be long enough to hold the doors open once the first has left.



This image shows the entire thing. It is top loading-bottom ejecting. I felt that in a combat situation this would work best; rather than having to flip the gun over you may simply load additional shells while it is still primed, if nessicary. in the design, the mag tube is around 2' long, and with 3" shells it should hold almost 8. 7+1 at least. I don't think this is too long, but am too tired to do anything about it and really it'd be really easy to shorten the design. I want something that is multi-purpose with this - Close combat, medium engagement, and long range. I'm also hoping to make it more of a "canister rifle" by making the shells accept nerf darts (I'm planning to use tagger darts since I don't have stephans), a wad of airsoft bb's for actual shotgun fire, and possibly single airsoft bb's.

I won't be able to begin construction 'till break (week and a half), and I want to have the design fairly well hammered out by then. Though I can't make any promises, my build vs. thought about building ratio is very bad (I've got a nifty hand cannon though).

Edited by Meaker VI, 07 December 2006 - 01:02 AM.

[SHADOW HUNTER ALPHA]

You ran into one of the same problems I did with the tube mag: how to stop the rest of the shells from popping out of the tube once one shell was already in the the carrier/chamber. I am still working on the solution, but the pics you put up here helped greatly with breaking the entire design down into more specific regions and systems.

[Ronster]

So, you are deciding to add the barrel above the barrel, eh?
Like the Halo shotgun. Cool.

Hey, a while back I found the perfect tube mag spring. All you need is the spring used for a spiral notebook! It might not be strong enough for heavy shells, but it's still the best I've found so far!

[Meaker VI]

Excellent idea Ronster, that sounds plausable. I'm not sure if you meant "barrel over barrel" though, it's mag-tube over barrel which is very much like the Halo 2 shotgun. I don't know if I posted it earlier, but I haven't worked on the plunger or fire control group much because I'm not very concerned with them; the community has provided several methods for successfully and reliably working both togeather. I was thinking of using something like Bolt's most recent trigger, and a floating plunger. Those will come later though.

Captain Slug PM'd me an excellent idea that would require disposing of the shells, shrinking the magtube accordingly, and making the carrier a tube that goes up and down in the chamber. Once at the top of the chamber, the dart would go in the carrier and then when it went back down it'd be easy to rig something to keep the darts in. Unless someone can figure out an idea for ejecting shells out of a cylindrical carrier within the chamber...

[CaptainSlug]

Meaker VI has been trying to pick my brain on this topic and I've given him what little I can offer while still having a head cold that is impairing my attention span.
What everyone may want to consider is simplifying the mechanisms involved rather than trying to replicate an actual shotgun. If you put the tube magazine inline with the barrel, the barrel ends up being much longer than needed and the whole weapon ends up really long. If you put the tube magazine inline with the plunger you save a ton of space and length.

As for the loading mechanism I suggested an elevator of sorts instead of a traditional carrier lever. The elevator slides vertically between the tube magazine and barrel, and when a shell is loaded inbetween the barrel and plunger chamber it blocks off the magazine. This mechanism could be used in two different ways depending on whether or not you felt that shells were needed. If you fill the tube magazine with darts that lack shells then the mechanism could be much simpler since you won't have to eject the shells. Having to eject shells introduces extra mechanical steps in the priming cycle that are more difficult to design.

There are two potential methods for ejecting the shell from this mechanism.

1. The "elevator" tube has an open front and an open back. A spring-loaded lever above the plunger chamber and at the same level as the magazine tube keeps all of the shells (full or empty) from being pushed out of the tube magazine. Have the shell move down between the barrel and plunger chamber, empty it by firing, then it's lifted back up to the magazine tube level. Briefly during the priming cycle the spring-loaded lever is tripped down and the emptied shell it allowed to be pushed out by the tube magazine spring, but the taper at the front of the shell allows it to rise back up before a second shell can eject. This area also doubles as the port for reloading.

2. Have a secondary shell ejection port on the underside of the gun. A more traditional breech design could be used for shell ejection since the shell itself is acting in some way as a barrel section and breech. The elevator in this configuration would simply be a follower rather than a hollow tube section.

Edited by CaptainSlug, 07 December 2006 - 10:10 PM.

[Meaker VI]

I didn't know you were sick Captain Slug, I'm sorry if I'm pestering you. Thank you for your help despite being sick though.

I should work on making more component diagrams for Captain Slug's designs and posting them for clarity, but until I can do that (no promises) I'd like to work out as many other kinks as possible. For example, the way it sounds for the first shell ejection method Captain Slug proposed it kinda seems like we still have the problem of all the shells possibly falling out. Only, instead of them just falling out all the time it'd be just when the chamber was up and could be timed so that they didn't.

And I'm not convinced that it's impossible to do with a lever carrier, so that isn't out of the running either.

Did anyone check out Torques Boomstick on the Hommades directory? It is a pump action shotgun, but with a gravity feed system instead of a forced feed system. And the writeup didn't seem very complete, but he did show all the parts. I also remember reading something about it's having problems because he used the wrong o-ring or something too...

[SHADOW HUNTER ALPHA]

I like the carrier assembly for my shotty better, especially because I already know how it would work and how I would integrate it into my design. I also like the tube mag below the barrel because it makes the design feel more like a conventional shotgun. This isn't to discredit any of your designs, because I think that they would work fine if you planned out all of the systems, but I seem to like sticking with my own plan. (I am also going to begin the carrier assembly this weekend, since I actually have some free time from all of my school projects.)

P.S.: I did see the Boomstick on the homemades directory.

[Flaming Hilt]

I'm with SHA. Again, Meaker and CS, your ideas are great and are probably going to be really cool, but I'm more of an aesthetic person; for me, the clip on a shotty should be below the barrel. Again, just personal preference.

I've now got a few more projects on my list before the shotty, so it'll be a while. Although I have been thinking what would be WAY easier than a carrier... a ramp.

...........\
............\
.............\
..............\
XXXXXXXXX\
___________\

Where the Xs, as anyone who has seen my schmatics before knows, constitute an extension spring. The ramp, of course, would a be a lot shallower.

The extension spring would allow one to open it (push the shelf up) to put shells in through the bottom, and then it would automatically close for shells to climb up.

I really don't see any problems with this, as long as it closes well after reloading and the bolt is able to catch the shell and push it over the next one in line there shouldn't be any problems.

[Meaker VI]

The design of my shotgun wouldn't need to be top loading, with minor modification you could make it bottom loading. All you'd practically have to do would be to flip everything except the pump. Then it would be bottom loading again.

Flaming Hilt, I'm not sure that a ramp alone would work. You need something to push the front of the shell up, otherwise it'll just get pushed back into the mag-tube by the bolt. Or flipped over... Though I suppose if you had a nearly flat ramp it might make it so the bolt could grab the shell... but that would unnessecarily complicate things. Your idea might work better with a regular spring, which would make it so you needed to pull back the ramp, but it would ease the problems you would have with shells coming out before the ramp was fully back in position otherwise.

I'm going to search around for a solution to the mag-tube/shells falling out issue....
[edit]
Victory is mine! The image is courtesy of www.alpharubicon.com, on this page. Toward the bottom of the page, he explains how to *safely* unload a shotgun, and in order to do it you are supposed to depress that little bent bugger on the right of the gun that's keeping the shells in.

This looks very easy to imcorporate into any of our designs, C. Slug's would push it out of the way with the round carrier-elevator, Flaming Hilt's would push it out of the way when in the down position, as would any of ours with carriers. Mine would be the "up" position, but the exact same theory applies for whichever way it is facing. All that i need to do to my design to make it work is to make the carrier have a bulge on one side that depresses the mag spring far enough to release the next shell. So, with this addition one of the major problems I had seen can be solved. Are there any other function-related issues that anyone sees that need addressing?

Edited by Meaker VI, 14 December 2008 - 11:13 PM.

[SHADOW HUNTER ALPHA]

Let's all take a minute and thank God that Meaker VI finally found the pic we were looking for. Now that that missing piece has been "revealed," it should be a simple matter to incorporate the part into the designs we have. All we have to do is figure out what to make the tab out of and how to attach it, and this project can finally get under way again.

P.S.: Flaming Hilt, your ramp could work, and if it is what you want to use in place of the carrier, go for it.

Edited by SHADOW HUNTER ALPHA, 09 December 2006 - 04:59 PM.

[Commonly Hunted]

Flaming Hilt, I was thinking the same thing about the ramp but I can't show you my designs because they aren't complete just yet. As soon as I get my design finished it will be up here and you will all see how a real Homemade Nerf Shotgun should look like.

Heh, 100th post.