doesn't fire yet, and needs a firing chamber, but this is a demo of how a true horizontal magazine (think the p90) can be used wherein the rounds are positioned perpendicular to the barrel, and spun to allow them to be fired. Currently the mag holds 18 rounds of green rods, but it can easily be extended to hold more. this would be most likely positioned so that what is here shown as yellow and white connectors in rows would be where the top rail would be, with the bolt handle right behind it. I have no clue if anyone wants to use this in a gun, I might try myself but I don't know how I'll do. if anyone wants be to do a full ible on it for their gun, or even just internals, ask me in the comments and I'll do so. I'll post a video of it in action as well but I need to see if it has enough interest beforehand as my network is really slow uploading images and video. Cheers!
Step 1: How to Make, in Very Crappy Pictures (sorry I've Got No Time for Making a Nice Instructible!)
Basically after this just make the bottom guide for the bolt as a main part of the gun so that when the bolt comes back, it stops where the opening for the rounds is right lined up with the half-3d piece so that the rounds can drop down and get caught and spun.