Fleeting Aether

At the moment I'm working on a p90 helix ramp magazine. I have the feeding drum and the ammo box made. I need some help getting the dual helix ramp correct for the shells to turn properly. Here's the current build.







All I need is a good CAD or other 3d rendition of a dual helix ramp for the rotating of the rounds to be fired. After that I can shape some insulation foam to the correct shape and report back with what I have (hopefully with the digital camera.) I'm actually in the process of building a prototype so it's more than just a theory. Whether it will work or not is yet to be discovered.

Edit: Oh and the materials I used so far are: two gatorade bottle lids(any wide mouth bottle lid will work), 1.5" stefans, insulation foam(the pink stuff at home depot), and tagboard.

Long time lurker, first time poster. So anyway, a couple of weeks ago I was brainstorming ideas of how to make a semi-auto nerf gun without the use of a plunger (I'm a sucker for cosmetics on guns). So I thought about how real guns work, and remembered that for the most part the power comes from the bullet itself, so I realized that I could make the shell and bullet do the work of the plunger tube and I came up with this little idea.



Basically the idea is that using the power of elasticity you could store kinetic energy in a spring or rubber band or other such elastic material, and have the dart be pushed right against the clip by the spring causing it to be stored under lots of pressure which would then be conferred to forward momentum when the dart is allowed to travel forward by aligning the shell with the barrel. So with that in mind all you would need theoretically is an advancing mechanism which could keep the shells from spilling out, or other things you wouldn't want to happen. Now I realize that this idea most likely will not have really great ranges, unless you find some really good springs to fit in your brass shells and that you need very dense Stefans to withstand being flattened by the spring but semi-auto at medium-close range while using a primary is nothing to laugh at. Suggestions welcome.