I know I haven't posted in a while but I just finished a major design and was wondering if anyone else has ever made anything like this. My idea was to build a device that could shoot three times in the absolute least amount of time possible. I'm fully aware of the various devices that joergsprave and others like have him designed that can be seen in various youtube videos, even printed and tried some out myself. But I found that many of these devices had a feed system that had to be fine-tuned to make it reliable, and all required some form of action between each shot that slowed things down. What I came up with was a simple stacked design that had three devices stacked on top of each other, held together using two brackets at one end and a specialized stock at the other end. There are three seperate triggers but with sufficient hand strength, a finger can be placed on each (similar to a musical instrument) and then three shots fired off in quick succession, or even at the same time.
The early prototype seen in this video:
worked well enough that I spent some time scale the design up, and then around another week to print all the various updated pieces. Being mostly made of copolymer with only a couple metal parts, weight isn't really an issue (under 3 lbs), the primary downside of the device is the amount of time it takes to reload (with practice, roughly 30 seconds to load all three shots using a special tool).
The prototype in the video would fire a 131 grain projectile at 120 ft/sec, the larger version can fire the same 131 grain projectile at speeds between 140 ft/sec and 160 ft/sec (depends on the bands used), or a 220 grain projectile at speeds between 120 ft/sec and 140 ft/sec. This isn't as powerful as some of the devices I have designed, but it's about the most power you can expect for a device with a draw length of 7.5 inch draw length. The prototype would have a lot of problems penetrating much beyond a empty cardboard box, the new device can easily penetrate into solid cardboard targets I use.
I'll add some video of how the new device operates once I have a chance to make it, things are kinda hectic right now with both work and the various holidays coming up but I hope to be able to make some video outdoors demonstrating the various devices I have built soon.