veginator

 

I've wondered if sprockets are the best way, or if a proper pawl setup would be better and NERF et. al. doesn't do it because they're used to turrets and turrets work fine for stock blasters.

 

Either way, I was thinking 1" 200 PSI PVC would be a good shell size. 3 darts should fit no problem, 4 if you cram them in, mega/rivals could also fit if you wanted. OD is 1.315" for all varieties of 1" PVC, ID is +/- 1.16-1.189". PVC because it'd be cheap enough to build a belt out of: 10' of the stuff would make ~40 links in the chain for ~$5 (plus whatever filler you use to make the barrels). When I was considering it more seriously, I was going to make a jig to just duct tape the shells together into a belt. Seemed like a good combination of simple, reliable, and cheap.

Oh wow, I misunderstood what you were asking for. For some reason I got in my head that you wanted to chain feed a doomsayer. So what you are asking for is a chain fed shotgun in the literal sense. That's a bit different than what I had in my head. Let me think for a bit on that.

Again, rifling isn't really what matters here. Check out Slug's recent thread about the VF1 barrel alongside the SCAR. Both were identical unless the fit wasn't right in the SCAR, then performance was better on the SCAR. The whole idea of fishing line is an adjustable elastic barrel, not to impart spin. People like JSPB and others who do it for spin are correlating two things and assuming causation. In terms of fluid dyanmics, it makes no sense that spin would help a nerf dart, DOOM wrote a dissertation-style nerf document that modeled a dart and came to the same conclusion, and cited evidence that spin doesn't help. DOOM'd document is an excellent read if you're up for it, its on his website, go read it.

 

What Meaker is getting at is there is zero advantage to turning/milling a rifled barrel for nerf. Either 3D print Slug's VF1 and tune the diameter, or use a SCAR barrel. 

 

 

I hope that you are either being flippant or are referring to the dimensions of some specific part, like a nerf dart or stock vulcan chain. The dimensions are dictated by the design that no one has come up with. Everyone and their little sister can CAD these days, that part is trivial. Spending the time to design, prototype, and revise is what they were asking of you, not simply drawing up someone else's work.

I'm not talking about using it for a dart. From the evidence slug has presented its obvious that this would not work on a dart. I'm talking about the rival rounds and making them more stable at a higher velocity. I only want to use a mill because I want to. I like to work with my hands, that's it.

Woah you have an engineering degree that obviously means you are a god of design and fabrication and make literally anything

I neither have a degree nor am I the god of fabrication. What I do have is a fairly well equipped machine shop and some advanced research equipment. I also have a little bit of fab experience with stuff like automotive intake manifolds, exhaust, and chassis bracing.

Woah woah woah engineer. Current SCAR methodology is just fishing line run through the pipe and anchored at either end. Try that first, then break out your fancy mill.

Fancy mill? Its just a vertical mill. Wouldn't be hard to put some barrel material in an indexing collet and start drilling some holes. I don't typically use the fancy cnc mill. Also, I always hated those fishing line and nail-on-a-stick methods for getting a rifled barrel.

A chain fed shotgun would be relatively easy in theory. Just replace the turret with a couple big sprockets like the vulcan has. Get me some dimensions and I can make a solidworks file simply enough. 

That's adorable.

 

To be clear, rifled barrels when used on darts are not used to impart spin. Anyone who claims that spin is the what makes the dart more accurate has a pretty elementary understanding of what's going on. I'm sure you already knew this though, being an engineering undergrad and all. The only reason that it's useful to change the twist ratio (a la Scar) is that doing so also changes the elastic inner diameter of the muzzle device. As you might imagine, more turns = smaller effective diameter.

 

Rifling and hop-up would be much more beneficial on a projectile with uniform density, like a rival round. As you nay surmise with your spud gun experience, hop up can increase the range and rifling the accuracy. I have seen some work with hop-up, but haven't seen much with rifling. That would be an interesting place to start if you're looking for a project.

Yeah I know, I tend to brag too much when I've been drinking.

I can think of a few ways to put some rifling inside a barrel. What is the current preferred barrel material for the rival rounds? Initial idea would be to mill a sleeve of tight barrel material and then slide it inside an outer barrel. Trying to make it out of one piece and be uniform would require a much more complex machining operation which I really don't feel like dealing with.

What about the 35 round drums? I know they weren't the greatest but they are certainly less unwieldy than a chain dangling down from the front.

Seeing as rifled barrels are becoming more common place on darts, I'm assuming similar tactics have been tried on the balls. What has been tried? From personal experience I know that, when fired fast enough from a barrel, golf balls will be unstable in flight unless you use a rifled barrel. Hell even a little back spin makes them much more stable at higher velocities.

I like the idea of a chain fed absolver but it doesn't really make a lot of sense with the all the high cap mags available now. I was talking to my brother and apparently whats keeping the power down on the ball shooters is the plunger size. Is this correct? I could solve that real quick on the lathe.

#humblebrag

Yeah bud. Want me to tell you all the ways I better than you?